If brethren dwell together, and one of them die, and have no son, the wife of the dead shall not be married without unto a stranger: her husband's brother shall go in unto her, and take her to him to wife, and perform the duty of a husband's brother unto her.
Then said Judah to Tamar his daughter-in-law, Remain a widow in thy father's house, till Shelah my son be grown up; for he said, Lest he also die, like his brethren. And Tamar went and dwelt in her father's house.
Turn again, my daughters, go your way; for I am too old to have a husband. If I should say, I have hope, if I should even have a husband to-night, and should also bear sons;
And Onan knew that the seed would 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 he should give seed to his brother.