And she conceived again, and bare a son; and she called his name Onan.
From the account of Judah's family lineage in Canaan.
King James Version (public domain)
Traditionally attributed to Moses · c. 13th century BC · The Pentateuch — Genesis, Exodus, Leviticus, Numbers, and Deuteronomy — is traditionally attributed to him
2And Judah saw there a daughter of a certain Canaanite, whose name was Shuah; and he took her, and went in unto her.
3And she conceived, and bare a son; and he called his name Er.
4And she conceived again, and bare a son; and she called his name Onan.
5And she yet again conceived, and bare a son; and called his name Shelah: and he was at Chezib, when she bare him.
6And Judah took a wife for Er his firstborn, whose name was Tamar.