Genesis 38:1-10

At that time, Judah left his brothers and went down to stay with a man of Adullam named Hirah. There Judah met the daughter of a Canaanite man named Shua. He married her and made love to her; she became pregnant and gave birth to a son, who was named Er. She conceived again and gave birth to a son and named him Onan. She gave birth to still another son and named him Shelah. It was at Kezib that she gave birth to him. Judah got a wife for Er, his firstborn, and her name was Tamar. But Er, Judah’s firstborn, was wicked in the LORD’s sight; so the LORD put him to death. Then Judah said to Onan, “Sleep with your brother’s wife and fulfill your duty to her as a brother-in-law to raise up offspring for your brother.” But Onan knew that the child would not be his; so whenever he slept with his brother’s wife, he spilled his semen on the ground to keep from providing offspring for his brother. What he did was wicked in the LORD’s sight; so the LORD put him to death also.