Leviticus 8:24

And he brought Aaron’s sons. — Having performed these symbolical acts upon the high priest, Moses now repeats the same in the case of the four ordinary priests. The right members were chosen for these symbolical acts because they are represented as the strongest, and are therefore most able to execute the will of God (see also Exodus 29:20). The cured leper had the same parts of the body touched with the blood of the trespass offering. (See Leviticus 14:14.)