Albert Barnes Commentary 1 Chronicles 2:55

"And the families of scribes that dwelt at Jabez: the Tirathites, the Shimeathites, the Sucathites. These are the Kenites that came of Hammath, the father of the house of Rechab." — 1 Chronicles 2:55 (ASV)

Kenites - It is remarkable that the Kenites—a people of a race quite distinct from the Israelites (Genesis 15:19)—should be attached to and, as it were, included in the descendants of Judah.

It seems, however, that the friendly feeling between the two tribes, based on the conduct of the Kenites at the time of the Exodus (Exodus 18:10–19; Numbers 10:29–32; 1 Samuel 15:6), led to their intermixture and almost amalgamation with the Israelites. Consequently, Kenite families not only dwelt among them but were actually regarded as being of one blood with them.