1 Chronicles 6:9

And Ahimaaz begat Azariah, and Azariah begat Johanan,

This link — Ahimaaz to Azariah to Johanan — belongs to the genealogy of Levi, specifically the priestly line from Aaron, forming part of the long lists of names in 1 Chronicles 4-19. That long series of names can look dry and uninteresting, for it is a list of names rather than an expressed promise.

These family records preserved proof of hereditary descent and the integrity of the tribes, showing that God kept careful records of His people. The full, carefully preserved priestly genealogy guarded the privileges of the priesthood, the fulfillment of prophecy and promise, and the Messianic hopes of Israel. After the exile such records were needed to assign land and to restore hereditary duties in the temple service. The genealogies of Judah and Levi alone remained unbroken until Christ's first advent, and the Aaronic priesthood continued until it was superseded by Christ's priesthood.

Compared with Ezra's shorter priestly lineage up to Aaron, this fuller genealogy supplies omitted links. It illustrates the Hebrew habit of compressing a genealogical series by giving part for the whole and calling a man the son of a third- or fourth-generation ancestor when the design is only to show relation to a remote ancestor rather than to spread out the whole family history. The omission in the shorter list is by selection for purpose and plan rather than by ignorance. The same habit must be allowed for in calculating chronology from genealogies, since much more time may have elapsed than would appear if the shorter series were supposed complete.