1 Chronicles 24
In this chapter we find the divisions of the priests. First, there is that which cannot be wanting in Chronicles: the flesh has been completely put aside and judged in the person of Nadab and Abihu. Then come Eleazar and Ithamar. On account of the unfaithfulness of Eli and his sons, Ithamar loses his preeminence under the reign of David and Solomon, and then under Christ's millennial reign, although the priesthood is not taken away from him (1 Chron. 24:3). Eleazar, through Zadok who is descended from him, occupies the first place on account of Phinehas' zeal. He becomes the founder of the faithful priesthood which will walk forever before the true Solomon in His kingdom (1 Sam. 2:25; Ezek. 48:11). David here distributes the priests into classes according to their chiefs: Zadok descending from Eleazar, and Ahimelech, from Ithamar. Abiathar, descending from Ithamar, was, as we know, driven from the priesthood by Solomon (1 Kings 2:26): but this fact is not mentioned in Chronicles, where we find the priesthood as well as the kingship established according to the counsels of God.
As we were saying, Eleazar occupies a place of special blessing: "And there were more head-men found of the sons of Eleazar than of the sons of Ithamar" (1 Chron. 24:4). There were sixteen heads of fathers' houses in the family of the former, eight in that of the latter. "And were they divided by lot" (1 Chron. 24:5). It was the will of God, and not that of man, that set them in courses, for before the gift of the Holy Spirit the lot was the sign of God's direct intervention without the will of man (Acts 1:26; Luke 1:9). "The princes of the sanctuary and the princes of God were from out of the sons of Eleazar and from among the sons of Ithamar" (1 Chron. 24:5), it is said, thus emphasizing the difference between these two families. "One father's house was drawn for Eleazar, and one drawn for Ithamar" (1 Chron. 24:6), so that the sons of Eleazar had a double portion. Thus there were twenty-four classes of priests according to God's thought. We see this order reproduced in the twenty-four elders—kings and priests—of Rev. 5.
In 1 Chron. 24:20-31 we find the numbering of the sons of Levi who still remained to be divided by lot. First (1 Chron. 24:20-25), the sons of Kohath (see Amram, 1 Chron. 24:20 and 1 Chron. 23:12), then, in 1 Chron. 24:26-31, the sons of Merari, Gershon having been counted as a single course on account of its fewness in number (1 Chron. 23:11). Note that the least among the Levites had the same portion as the chief fathers in the division by lot according to the Lord's free choice (1 Chron. 24:31).