Leviticus 9 · a question people ask
What did Aaron say when he blessed the people?
The chapter doesn't say. It gives only what he did: "Aaron lifted up his hands toward the people, and blessed them" (9:22), and then Moses and Aaron together "blessed the people" (9:23). Later the LORD gives Aaron and his sons words for blessing: "This is how you shall bless the children of Israel" (Numbers 6:23), beginning, "The LORD bless you, and keep you" (Numbers 6:24). Numbers doesn't say whether those were the words used on this day.
The verses
“Aaron lifted up his hands toward the people, and blessed them; and he came down from offering the sin offering, and the burnt offering, and the peace offerings. Moses and Aaron went into the Tent of Meeting, and came out, and blessed the people; and the LORD’s glory appeared to all the people.”
“The LORD spoke to Moses, saying, “Speak to Aaron and to his sons, saying, ‘This is how you shall bless the children of Israel.’ You shall tell them, ‘The LORD bless you, and keep you. The LORD make his face to shine on you, and be gracious to you. The LORD lift up his face toward you, and give you peace.’ “So they shall put my name on the children of Israel; and I will bless them.””