Genesis 38:6 ASV

⁴  And she conceived again, and bare a son; and she called his name Onan.

⁵  And she yet again bare a son, and called his name Shelah: and he was at Chezib, when she bare him.

⁶  And Judah took a wife for Er his first-born, and her name was Tamar.

⁷  And Er, Judah's first-born, was wicked in the sight of Jehovah. And Jehovah slew him.

⁸  And Judah said unto Onan, Go in unto thy brother's wife, and perform the duty of a husband's brother unto her, and raise up seed to thy brother.