Leviticus - Chapter 8

After all the preparations it is now time to ordain Aaron and his sons as priests.  The first act was carried out by Moses:

Moses brought Aaron and his sons forward and washed them with water.

At the start of Jesus ministry we see the same thing happen (in Matthew chapter 3):

Jesus came from Galilee to the Jordan to be baptised by John.  But John tried to talk him out of it. “I am the one who needs to be baptized by you,” he said, “so why are you coming to me?” But Jesus said, “It should be done, for we must carry out all that God requires.” So John agreed to baptize him.