Genesis 38:1-6

About this time, Judah left home and moved to Adullam, where he stayed with a man named Hirah. There he saw a Canaanite woman, the daughter of Shua, and he married her. When he slept with her, she became pregnant and gave birth to a son, and he named the boy Er. Then she became pregnant again and gave birth to another son, and she named him Onan. And when she gave birth to a third son, she named him Shelah. At the time of Shelah’s birth, they were living at Kezib. In the course of time, Judah arranged for his firstborn son, Er, to marry a young woman named Tamar.