Leviticus 8:2-6

“Take Aaron and his sons with him, and the garments and the anointing oil and the bull of the sin offering, and the two rams and the basket of unleavened bread, and assemble all the congregation at the doorway of the tent of meeting.” So Moses did just as the LORD commanded him. When the congregation was assembled at the doorway of the tent of meeting, Moses said to the congregation, “This is the thing which the LORD has commanded to do.” Then Moses had Aaron and his sons come near and washed them with water.