Genesis 38:8

And Judas said to Aunan, Go in to thy brother's wife, and marry her as her brother-in-law, and raise up seed to thy brother.

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

Judah said to Onan, “Go in to your brother’s wife, and perform the duty of a husband’s brother to her, and raise up offspring for your brother.”