I Chronicles 4:21

The sons of Shelah, the son of Judah, were,.... The genealogy of the posterity of Judah, in the lines of Pharez and Zerah, being given, and very largely in that of the former, because of the honour of David, and his kingdom, which sprang from thence, as Jarchi observes, and also the King Messiah, the writer returns to give an account of his posterity by Shelah, a son he had by the daughter of Shuah, Gen 38:2 and the only one that had children: which were as follow: Er the father of Lecah: prince of a city of this name in the tribe of Judah; Shelah gave him the name of Er, in memory of his brother, Gen 38:3, and Laadah the father of Mareshah; prince of a city of this name in the same tribe, Jos 15:44. and the families of the house of them that wrought fine linen, of the house of Ashbea; which last clause explains what house these families were of, which sprang from Shelah, and were employed in making fine linen; the Targum adds, for the garments of kings and priests, or for the curtains of the tabernacle, as Jarchi; for not with the Egyptians and Greeks only fine linen was made, but among the Hebrews, as Pausanias (f) testifies. (f) Eliac. 1. sive, l. 5. p. 294.

In this chapter we have, I. A further account of the genealogies of the tribe of Judah, the most numerous and most famous of all the tribes. The posterity of Shobal the son of Hur (Ch1 4:1-4), of Ashur the posthumous son of Hezron (who was mentioned, Ch1 2:24), with something particular concerning Jabez (Ch1 4:5-10), of Chelub and others (Ch1 4:11-20), of Shelah (Ch1 4:21-23). II. An account of the posterity and cities of Simeon, their conquest of Gedon, and of the Amalekites in Mount Seir (v. 24-43).

4:21-23 Now that Judah’s descendants through his wife Tamar have been recorded (2:4–4:20), the descendants of Shelah, Judah’s third son through Bathshua, are listed (see 2:3; Gen 38:2, 5).