After breaking down the different family lines of the Levites the author provided the specific Levitical line of Aaron. Since Aaron's sons, Nadab and Abihu died when they offered sinfully, the lines of Eleazar and Ithamar were left for executing the priestly duties. We are told how David further divided the duties among the families of these two men. Eleazar, through whom the high priestly line descended, had a larger family than did Ithamar. 24 lots were drawn from among these priests for the various services that only the priests, the descendants of Aaron, were appointed by God to do. Then the rest of their near relations, those descended from Kohath and Merari, were divided accordingly by lots.
One note of interest is that Zachariah, the father of John the Baptist, descended from Abijah. This means that his family served in the eighth lot. (Compare 24:10 to Luke 1:5.) John never served as a priest like his father did, but he served God directly - and by God's authority - by preparing the way of the Lord. He did this by preaching the gospel of repentance and faith and by baptizing those who comprise the first church. Zachariah and John the Baptist provided the link between the Temple sacrifices of offering the blood of bulls, goats, and lambs, and the sacrifice of The Lamb which those animal sacrifices pictured.
Does God issue any commands?
God did not speak, but David was clearly following God's commands found in the Pentateuch concerning the service of the Levites and the priests when he assigned their duties.
Does God make any promises?
God did not speak.
Does this chapter teach anything about Jesus?
The job of the priests was to offer the sacrifices and lead the worship. The animal sacrifices all pictured the coming Messiah, the Lamb of God who would be slain for the sins of the world. Meticulous details were given and kept here in the Chronicles for the Levites returning from captivity. Everything was also recorded and kept in order for the coming of the Christ, even down to the names of the families that took turns ministering in the Temple service.
Does this chapter teach anything about yet-future events?
Everyone had their assigned responsibilities when it came to service to God. Surely in the time of the eternal future each person will receive their assignment in God's economy. God always does things decently and in order. It is only when sin interferes that responsibilities become difficult or impossible. There will be no sin to contend with so the jobs truly will be enjoyable and light. Perhaps that is another aspect of Jesus' saying that His yoke is easy and His burden is light. He also told all who are weary to come to Him because He will give us rest. When we are assigned our responsibilities they will not be wearisome or hard for us but will be enjoyable and completed out of hearts full of thanksgiving to the God that provided Himself as our sacrifice!