In this chapter Aaron lights the lamps inside the Holy Place, the Levites belong to the LORD instead of all the first born, and God explains retiring the Levites at the age of 50. Nothing really “happens” but we will observe a milestone tomorrow.

Numbers 8 

The LORD spoke to Moses, saying:

2 “Speak to Aaron and say ‘When you light the lamps, the seven lamps shall give light in front of the lampstand.’”

3 And Aaron did so; he set the lamps to give light in front of the lampstand, as the LORD commanded Moses.

4 The lampstand was made of beaten gold; the shaft and the flowers of it were beaten work: according to the pattern which the LORD showed Moses, so he made the lampstand. 

5 The LORD spoke to Moses, saying:

6 “Take the Levites from among the children of Israel, and cleanse them.

7 Here’s what you must do to cleanse them: Sprinkle them with the water of purification, and let them shave their whole body, and let them wash their clothes, and so make themselves clean.

8 Then let them take a young bull with his grain offering, fine flour mingled with oil, and another young bull you shall take for a sin offering.

9 You shall bring the Levites before the tent of meeting: and you shall gather the whole assembly of the children of Israel together:

10 Then you shall bring the Levites before the LORD: and the children of Israel shall put their hands on them.

11 Aaron shall offer the Levites before the LORD for an offering of the children of Israel, that they may execute the service of the LORD.

12 The Levites shall lay their hands on the heads of the bulls: and you shall offer the one for a sin offering, and the other for a burnt offering, to the LORD, to make atonement for the Levites.

13 And you shall set the Levites before Aaron, and before his sons, and offer them for an offering to the LORD.

14 In this way you will separate the Levites from among the children of Israel: and the Levites shall be mine.

15 After that the Levites will go in to do the service of the tent of meeting: and you shall cleanse them, and offer them for an offering.

16 For they are wholly given to me from among the children of Israel; instead of every one that opens the womb; instead of the firstborn of all the children of Israel, I have taken the Levites. 

17 For all the firstborn of the children of Israel are mine, both man and animal: on the day that I struck every firstborn in the land of Egypt I sanctified them for myself.

18 I have taken the Levites for all the firstborn of the children of Israel.

19 And I have given the Levites as a gift to Aaron and to his sons from among the children of Israel, to do the service of the children of Israel in the tent of meeting, and to make atonement for the children of Israel: that there be no disease among the children of Israel, when they come near to the sanctuary.

20 So Moses, Aaron, and all the congregation of the children of Israel, did to the Levites according to all that the LORD commanded Moses concerning the Levites, the children of Israel did to them.

21 The Levites were purified, and they washed their clothes; and Aaron offered them as an offering before the LORD; and Aaron made atonement for them to cleanse them.

22 After that the Levites went in to do their service in the tent of meeting before Aaron, and before his sons: as the LORD had commanded Moses concerning the Levites, so they did. .

23 The LORD spoke to Moses, saying:

24 “This applies to the Levites: from 25 years old and upward they shall go on duty in the service of the tent of meeting.

25 And from the age of 50 years they shall cease in the service of it, and shall serve no more:

26 But shall minister with their brothers in the tent of meeting, to keep the charge, and shall do no service. This is how you are to deal with the Levites regarding their duties. 

See also: Numbers 8 in ESV, HCSB, NASB and NIV via Bible Gateway.