Psalm 51 is called "A prayer of repentance".

Its heading says it is a psalm of David from when Nathan the prophet reprimanded him after he had gone in unto Bathsheba. It's a cry of despair, full of deep repentance and the plea to be cleansed from the sins he has committed. The psalm shows a clear pattern through its words; by openly acknowledging the sin the speaker gets more understanding about the way of the Lord and about life. The psalm also shows a growing assurance and trust in the Lord and his acceptance of this cry.

This psalm, at a deeper level, also describes Jesus’ prayer to overcome the sins of his human nature which he took upon himself in becoming human. The Lord, unlike David, didn't give into temptations – John 8:46 has the Lord asking, “Which of you convicts me of sin?” – so His prayer is to have the strength to withstand the tendencies inherent in his human nature. The Lord was severely tempted in his humanity.

For us, this psalm is one we can relate to and feel is our own prayer when we see the ways in which our thoughts rise up out of our self-love or our proprium (our selfhood). True repentance is not remorse for some wrong we have done, although this can be part of our spiritual progress; it has far more to do with us giving our attention to thoughts and moods which suddenly rise up and plague our intention to be true to the Lord. (Divine Providence 121, 122)

This psalm mentions things which have to do with the Lord and things which have to do with us. Words like "mercy, loving kindness, just, judge, washing, presence, and good pleasure" speak about the Lord, while "transgressions, iniquities, evils, and sins" speak about us. The overall idea is that the Lord longs to give to us what is his, so that we know he is there with us and that he completely understands our human frailty. In being what we are like in ourselves, we will keep going astray. We continually need to bring ourselves before the Lord to be restored.

The Lord’s mercy is the His wish to save us and regenerate us, so that we will be drawn - and wish to be drawn - to heaven, which is where the Lord is. Mercy is not instant in its activity, but it is perpetual. (See Heaven and Hell 522)

‘Washing’ is another divine quality, but we need to be careful in understanding it. It is not the Lord washing our wrongs away as if they had never been done. Our wrongs may need to be brought back to us, not to taunt us, but to remind us of our need of the Lord and our wish to do no more wrongdoing. The true idea of washing is for us to ‘wash ourselves’ and to feel we have been washed, so that we can go forward stronger than we were. (See Divine Providence 151 and Apocalypse Explained 475.5)

‘Transgressions’ are evils we might do which come from a perverted understanding. (Arcana Caelestia 9156)

‘Iniquities’ are evils we do intentionally because we have twisted our thinking to justify doing them (Apocalypse Explained 475)

‘Evils’ are what we do because we are born with an imperfect human nature. (See The New Jerusalem and its Heavenly Doctrine 79 near the end)

‘Sins’ are evils we do intentionally because a love of evil has taken hold of us. (Arcana Caelestia 5726)

The phrase “Purge me with hyssop” means being cleansed by external truths or truths which we see and which confront us, demanding that we correlate our life to them. (Arcana Caelestia 7918)

The phrase “Let the bones which you have broken, rejoice” is describing the appearance to us that during temptation the Lord has broken us, whereas the very opposite is true, that the Lord is defending us and being our bones. So in truth, we may rejoice. ‘Bones’ spiritually mean truths because bones support the body and truths the spirit. (Arcana Caelestia 3812.8)

Overall, this is a psalm which, for us, can help us move on from seeing the number and range of our imperfections through to understanding, appreciating and acting on the truth that the Lord can and will lead us to restoration and wholeness if we go to Him.

2180. 'And took a young bull, tender and good' means a celestial-natural which the rational took to itself in order that it might join itself to perception from the Divine. This is clear from the meaning of 'a young bull' or 'a son of an ox' in the Word as natural good. And because the subject is the Lord's Rational, it is called 'tender' from the celestial-spiritual, which is truth grounded in good, and 'good' from the celestial itself, which is good itself. Within the genuine rational there is both the affection for truth and the affection for good, but that which is first and foremost there is the affection for truth, as shown already in 2072. This explains why 'tender' is mentioned before 'good'; but even so, as is quite usual in the Word, both are mentioned on account of the marriage of truth and good which is referred to above in 2173.

[2] That 'a young bull' or 'a son of an ox' means the celestial-natural, or what amounts to the same, natural good, becomes especially clear from the sacrifices, which were the principal representatives in the worship of the Hebrew Church and after this of the Jewish Church. Their sacrifices were made either from the herd or from the flock, thus from animals of various kinds that were clean, such as oxen, young bulls, he-goats, sheep, rams, she-goats, kids, and lambs, besides doves and fledgling pigeons. All of these creatures meant the internal features of worship, that is, celestial and spiritual things, 2165, 2177, those from the herd meaning celestial-natural, those from the flock celestial-rational. Because both of these - natural things and rational things - are more and more interior and are various, so many genera and so many species of these creatures were therefore employed in sacrifices. This fact becomes clear also from its being laid down as to which creatures were to be offered in burnt offerings and also which in every kind of sacrifice - the daily sacrifices; those offered on sabbaths and at festivals; those made as free-will, eucharistic, or votive offerings; and those offered in purifications, cleansings, and also in inaugurations. Which creatures were to be used, and how many, in each kind of sacrifice is mentioned explicitly. This would never have been done unless each one had had some specific meaning, as is quite evident from those places where the sacrifices are the subject, as in Chapter 29 of Exodus; Chapters 1, 3, 4, 9, 16, and 23 of Leviticus; and Chapters 7, 8, 15, and 29 of Numbers. But this is not the place to explain what each one meant. The situation is similar in the Prophets where those animals are mentioned, from which it may become clear that young bulls meant celestial-natural things.

[3] That none but heavenly things were meant becomes clear also from the cherubim seen by Ezekiel and from the living creatures before the throne which were seen by John. Regarding the cherubim the prophet says,

The likeness of their faces was the face of a man (homo); and they four had the face of a lion on the right side; and they four had the face of an ox on the left side; and they four had the face of an eagle. Ezekiel 1:10.

Regarding the four living creatures before the throne John says,

Around the throne were four living creatures - the first living creature was like a lion, the second living creature like a young bull, the third living creature had a face like a man (homo), the fourth living creature was like a flying eagle - saying, Holy, holy, holy is the Lord God Almighty, who was, and who is, and who is to come. Revelation 4:7-8.

Anyone may see that holy things were represented by the cherubim and these living creatures, thus also by the oxen and young bulls in the sacrifices. The same applies in the prophecy of Moses concerning Joseph,

Let it come upon the head of Joseph and upon the crown of the head of the Nazirite among his brothers. The firstborn of his ox has honour, and his horns are the horns of a unicorn; with these he will thrust the peoples together, to the ends of the earth. Deuteronomy 33:16-17.

These words are not intelligible to anyone unless he knows what ox, unicorn, horns, and many other things mean in the internal sense.

[4] As for sacrifices in general they were indeed commanded to the Israelites through Moses. But the Most Ancient Church which existed before the Flood never knew anything at all about sacrifices, nor did it ever enter their minds to worship the Lord by the slaughtering of animals. The Ancient Church which existed after the Flood knew nothing about it either. Representatives did indeed exist there, but not sacrifices. These were first introduced in the subsequent Church called the Hebrew Church, and from there they spread to the gentile nations, and even to Abraham, Isaac, and Jacob, and so to Jacob's descendants. The fact that the gentile nations had sacrificial worship has been shown in 1343, and the fact that Jacob's descendants also had such worship before they left Egypt, thus before sacrifices were commanded through Moses on Mount Sinai, becomes clear from Exodus 5:3; 10:25, 27; 18:12; 24:4-5.

[5] This is especially clear from their idolatrous worship in front of the golden calf, regarding which the following is said in Moses,

Aaron built an altar in front of the calf, and Aaron made a proclamation and said, Tomorrow there will be a feast to Jehovah. And they rose up early the next morning and presented burnt offerings and brought peace offerings. And the people sat down to eat and drink, and rose up to play. Exodus 32:5-6.

This happened while Moses was on Mount Sinai, and so before the command came to them regarding the altar and the sacrifices. That command came to them for the reason that sacrificial worship among them had been turned, as it had among the gentiles, into idolatrous worship, from which they could not be drawn away because they looked upon it as-the chief holy thing. Once something has been implanted in people from their earliest years as being holy, the more so if received from their fathers, and thus is inrooted, the Lord in no way breaks it - provided it is not contrary to order itself - but bends it. This was the reason for its being laid down that the sacrificial system should be established, such as one reads in the books of Moses.

[6] The fact that sacrifices were by no means acceptable to Jehovah, and so were merely permitted and tolerated for the reason just stated, is quite evident in the Prophets. Concerning them the following is said in Jeremiah,

Thus said Jehovah Zebaoth, the God of Israel, Add your burnt offerings on to your sacrifices, and eat the flesh. I did not speak with your fathers and I did not command them on the day I brought them out of the land of Egypt on the matters of burnt offering and sacrifice. But this matter I commanded them, saying, Obey My voice, and I will be your God. Jeremiah 7:21-23.

In David,

O Jehovah, sacrifice and offering You have not desired; burnt offering and sin-sacrifices You have not sought. I have delighted to do Your will, O my God. Psalms 40:6, 8.

In the same author,

You do not delight in sacrifice that I should give it; burnt offering You do not accept. The sacrifices of God are a contrite spirit. Psalms 51:16-17.

In the same author,

I will not take any young bull from your house, nor he-goats from your folds. Sacrifice to God confession. Psalms 50:9, 14; 107:21-22; 116:17; Deuteronomy 23:18.

In Hosea,

I desire mercy and not sacrifice, and the knowledge of God rather than burnt offerings. Hosea 6:6.

Samuel said to Saul,

Has Jehovah great delight in burnt offerings and sacrifices? Behold, to be submissive is better than sacrifice, to be obedient than the fat of rams. - 1 Samuel 15:22.

In Micah,

With what shall I come before Jehovah and bow myself to God on high? Shall I come before Him with burnt offerings, with calves a year old? Will Jehovah be pleased with thousands of rams, with tens of thousands of rivers of oil? He has shown you, O man, what is good; and what does Jehovah require of you but to carry out judgement, and to love mercy, and to humble yourself by walking with your God? Micah 6:6-8.

[7] From these quotations it is now evident that sacrifices were not commanded but permitted, and also that in sacrifices nothing else was regarded except that which was internal, and that it was that which was internal that was pleasing, not that which was external. For this reason also the Lord abolished them, as was also foretold through Daniel in the following words when he was speaking about the Lord's Coming,

In the middle of the week He will cause the sacrifice and the offering to cease. Daniel 9:27.

See what has been stated about sacrifices in Volume One, in 922, 923, 1128, 1823. As for 'the young bull' which Abraham made ready or prepared for the three men, the meaning is similar to that of the same animals when used in sacrifices. That it had a similar meaning becomes clear also from the fact that he told Sarah to take three measures of fine flour. Regarding the fine flour that went with the offering of a young bull the following is said in Moses - referring to when they were to come into the land,

When you make ready a young bull for a burnt offering or a sacrifice in the declaring of a vow, or for peace offerings to Jehovah, you shall bring with the young bull a minchah of three tenths of fine flour mixed with oil. Numbers 15:8-9.

Here similarly the number 'three' appears, though three 'tenths' here but three 'measures' in Abraham's instruction to Sarah. But only two tenths went with the offering of a ram, one tenth with that of a lamb, Numbers 15:4-6.