Genesis 38:7 (KJV)

And Judah saw there a daughter of a certain Canaanite, whose name was Shuah; and he took her, and went in unto her.

And she conceived, and bare a son; and he called his name Er.

And she conceived again, and bare a son; and she called his name Onan.

And she yet again conceived, and bare a son; and called his name Shelah: and he was at Chezib, when she bare him.

And Judah took a wife for Er his firstborn, whose name was Tamar.

And Judah said unto Onan, Go in unto thy brother's wife, and marry her, and raise up seed to thy brother.

And Onan knew that the seed should not be his; and it came to pass, when he went in unto his brother's wife, that he spilled it on the ground, lest that he should give seed to his brother.

And the thing which he did displeased the LORD: wherefore he slew him also.

Then said Judah to Tamar his daughter in law, Remain a widow at thy father's house, till Shelah my son be grown: for he said, Lest peradventure he die also, as his brethren did. And Tamar went and dwelt in her father's house.

And in process of time the daughter of Shuah Judah's wife died; and Judah was comforted, and went up unto his sheepshearers to Timnath, he and his friend Hirah the Adullamite.