Chapter 40

Tabernacle to be erected the first day of the first month.  This is the same month that they left Egypt.  So they  have been encamped around Sinai for a year.  An MSB note on vs 17 gives some more detail.  The book of Leviticus was given in the first month of that second year, still at Mt. Sinai.  That is why it is next.  Numbers begins with the people still in this camp in the second month of that second year.  So this has become a very long term camp out, living in tents, and awaiting God's word.  Would we stick it out this long?  Have to give Israel credit, they did wait here for God's direction. 

God tells Moses to set everything up, and to consecrate things with oil as he goes.  Once all the furniture is set up and consecrated, this:

12 Then you shall bring Aaron and his sons to the entrance of the tent of meeting and shall wash them with water 13 and put on Aaron the holy garments. And you shall anoint him and consecrate him, that he may serve me as priest. 14 You shall bring his sons also and put coats on them, 15 and anoint them, as you anointed their father, that they may serve me as priests. And their anointing shall admit them to a perpetual priesthood throughout their generations." [Exo 40:12-15 ESV]

So Aaron and his sons are washed with water, anointed, and consecrated to the service of God as priests, forever.

32 When they went into the tent of meeting, and when they approached the altar, they washed, as the LORD commanded Moses. [Exo 40:32 ESV]

Each time, they wash.  This is an important part of service.

The cloud descends in the tabernacle.  From then on, they move when the cloud ascends and they stay put until it ascends again.

So Exodus began with the oppression of Israel by a new Pharoah, sometime before the birth of Moses, and ends with the initial setting up of the Tabernacle, built according to God's own instruction.  God begins events at the beginning of Exodus that culminate with Him descending in a cloud over the Tabernacle.  All of Exodus has led to God's taking up residence among His chosen people.