Arcana Coelestia #1020
1020. That these things are meant becomes clear from the fact that everything put together as history from Genesis 1 down to Eber in Chapter 11 means something different from what appears in the letter, and from the consideration that the historical narratives there are purely made-up history customary among the most ancient people. When attesting the truth of some matter they would say that 'Jehovah said it'. Here however 'God' is used because the subject is the spiritual Church. And they did the same when anything true was being, or had been, put into effect.
Arcana Coelestia #1429
1429. 'Abram was a son of seventy-five years' means that as yet there was not so much of the Divine. This becomes clear from the meaning of the number 'five' as that which is small, and of the number 'seventy' as that which is holy. That 'five' means that which is small has been shown already in 649, and that 'seventy' or 'sever' that which is holy in 395, 433, 716, 881. Here, since seventy is used in reference to the Lord, it means that which is Divine and holy. Furthermore that the numbers 1 giving Abram's years have a different meaning in the internal sense may become clear from what has been stated and shown already about years and numbers in 482, 487, 493, 575, 647, 648, 755, 813, and from the fact that not one tiny expression or part of a letter exists in the Word that does not carry an internal sense. And unless it embodied things that are spiritual and celestial no mention would ever have been made of Abram's being at that time 'a son of seventy-five years', or of this event taking place when he was that age, as is also clear from other numbers, both of years and of quantities, that are given in the Word.
Footnotes:
1. i.e. the numbers 5, 70
In the Latin and in the Hebrew the words are literally Abram was a son of five years and seventy years.