Rashi on Exodus 29:9/רש"י על שמות כ״ט:ט׳

1והיתה להם AND SHALL BE UNTO THEM This “filling of hands” shall be for an everlasting priesthood.

2ומלאת AND THOU SHALT “FILL” by means of these following matters

3יד אהרן ויד בניו AARON’S HAND AND HIS SONS’ HANDS in the appointment and assigment to the priesthood.