Genesis 22:24

22:24 His concubine, whose name was Reumah, also bore him children – Tebah, Gaham, Tahash, and Maacah.

Genesis 25:6

25:6 But while he was still alive, Abraham gave gifts to the sons of his concubines ¹  and sent them off to the east, away from his son Isaac. ² 

Genesis 36:12

36:12 Timna, a concubine of Esau’s son Eliphaz, bore Amalek to Eliphaz. These were the sons ³  of Esau’s wife Adah.

Genesis 35:22

35:22 While Israel was living in that land, Reuben had sexual relations with ⁴  Bilhah, his father’s concubine, and Israel heard about it.

Jacob had twelve sons:

[25:6]  ¹ tn Heb “the sons of the concubines who [belonged] to Abraham.”

[25:6]  ² tn Heb “And he sent them away from upon Isaac his son, while he was still living, eastward to the land of the east.”

[36:12]  ¹ tn Or “grandsons” (NIV); “descendants” (NEB).

[35:22]  ¹ tn Heb “and Reuben went and lay with.” The expression “lay with” is a euphemism for having sexual intercourse.