Arcana Coelestia # 3137
3137. 'At the spring' means the enlightenment of them from Divine truth. This is clear from the meaning of 'a spring' as truth, dealt with in 2702, 3096, here Divine truth, as above in 3131. Because the Word is Divine truth it is therefore called 'a spring'. That 'standing at the spring' here embodies in the internal sense the enlightenment of things in the natural man follows from the train of thought; for where Divine truth is, enlightenment is there.
Wash
“Washing” in the Bible represents purification - unsurprisingly! Washing dirt from the skin symbolizes using true ideas from the Lord to remove evil desires and false ideas from our minds. This is the reason that washing was such an integral part of ritual; cleaning the body to perform physical acts of worship - something with no actual spiritual value - is symbolic of repenting our evils and falsities as part of worshiping the Lord.