Numbers 18:4

18:4 They must join with you, and they will be responsible for the care of the tent of meeting, for all the service of the tent, but no unauthorized person may approach you.

Genesis 29:34

29:34 She became pregnant again and had another son. She said, “Now this time my husband will show me affection, because I have given birth to three sons for him.” That is why he was named Levi.