Exodus 29:24

Put all in the hands of Aaron] thus inducting him and his sons into the duties of their office. The 'waving' consisted in moving the offerings horizontally in the direction of the sanctuary, in token that they were first presented to God and then returned by Him to the officiating priests. This ceremony was performed at the presentation of a peace offering (Leviticus 7:28), of the first fruits of harvest (Leviticus 23:11), and of the two loaves at the Feast of Weeks (Leviticus 23:20), and also in connexion with the cleansing of a leper (Leviticus 14:12; Leviticus 14:24): see also on Numbers 8:21.