Albert Barnes Commentary 1 Chronicles 7:2

"And the sons of Tola: Uzzi, and Rephaiah, and Jeriel, and Jahmai, and Ibsam, and Shemuel, heads of their fathers` houses, [to wit], of Tola; mighty men of valor in their generations: their number in the days of David was two and twenty thousand and six hundred." — 1 Chronicles 7:2 (ASV)

Whose number was in the days of David... This passage seems to indicate that the writer had access to the statistics of the tribes collected by David when he sinfully numbered the people. The numbers given in 1 Chronicles 7:4–5 probably came from the same source.