Eleazar and Ithamar were Aaron’s two remaining sons (Exodus 6:23).
let your hair become disheveled: In biblical times, this and similar practices showed grief (see Genesis 37:29; 44:13; Deuteronomy 14:1; 2 Samuel 1:11; Job 1:20; Jeremiah 16:6; 47:5). As high priest, Aaron could not participate in these ceremonies or show his grief (Leviticus 21:10). This rule also applied to Eleazar and Ithamar. If God’s representatives had shown grief, people might have thought they disagreed with God’s justice. But the common people were allowed to mourn.