Biography of Hamul

Genesis 46

12 And the sons of Judah; Er, and Onan, and Shelah, and Pharez, and Zarah: but Er and Onan died in the land of Canaan. And the sons of Pharez were Hezron and Hamul.

Numbers 26

19 The sons of Judah were Er and Onan: and Er and Onan died in the land of Canaan.

20 And the sons of Judah after their families were; of Shelah, the family of the Shelanites: of Pharez, the family of the Pharzites: of Zerah, the family of the Zarhites.

21 And the sons of Pharez were; of Hezron, the family of the Hezronites: of Hamul, the family of the Hamulites.

22 These are the families of Judah according to those that were numbered of them, three score and sixteen thousand and five hundred.

1 Chronicles 2

5 The sons of Pharez; Hezron, and Hamul.

From Jewish Encyclopedia, by Emil G. Hirsch M. Seligsohn:

The younger son of Pharez, Judah's son by Tamar, and head of the family of the Hamulites (Gen. xlvi. 12; Num. xxvi. 21; I Chron. ii. 5).E.