Exodus 29:1-4

“And this is what you shall do to them to hallow them for ministering to Me as priests: Take one young bull and two rams without blemish, and unleavened bread, unleavened cakes mixed with oil, and unleavened wafers anointed with oil (you shall make them of wheat flour). You shall put them in one basket and bring them in the basket, with the bull and the two rams. “And Aaron and his sons you shall bring to the door of the tabernacle of meeting, and you shall wash them with water.