Charles Ellicott Commentary Exodus 29:35

"And thus shalt thou do unto Aaron, and to his sons, according to all that I have commanded thee: seven days shalt thou consecrate them." — Exodus 29:35 (ASV)

THE SEVENFOLD REPETITION OF THE CONSECRATION CEREMONIAL.

Seven days shalt thou consecrate them. —The number seven possessed an ideal completeness, resting on the primeval facts of creation (Genesis 1:2). It is the number almost exclusively used under the old covenant, when acts are to attain their result by repetition. (Leviticus 4:17; Leviticus 8:11; Leviticus 14:7; Leviticus 16:14; Numbers 19:4; Joshua 6:4; 1 Kings 18:43; 2 Kings 5:10; Psalms 119:164; etc.) Here we are to understand a sevenfold repetition of the entire ceremonial of consecration. (See Leviticus 8:33-34.)