1. They divided them impartially (1-19)
Aaron had four sons, but two died tragically while offering unauthorized fire before the LORD. The remaining two, Eleazar and Ithamar, had male descendants who served as priests. David separated them into divisions for their appointed order of ministering, by casting lots. There was no partiality or favoritism. The 24 heads of families took turns in order (7-18). They followed regulations that were prescribed by Aaron and commanded by God (19). Casting lots avoided partiality and left the order up to God.
2. The oldest and youngest were treated the same (20-31)
The Levites were also ordered in their service by casting lots. Age did not matter. The families of oldest and youngest brothers were treated the same in their temple service. God's people must have mutual respect as God's servants and trust God's sovereign leading.