Genesis 38:8

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

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.”

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