If brethren dwell together, and one of them dies, and has no child, the wife of the dead shall not marry outside unto a stranger: her husband's brother shall go in unto her, and take her to him as wife, and perform the duty of a husband's brother unto her.
Then said Judah to Tamar his daughter-in-law, Remain a widow at your father's house, till Shelah my son is grown: for he said, Lest perhaps he die also, as his brothers did. 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 have a husband also tonight, and should also bear sons;
And Onan knew that the descendant 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 that he should give a descendant to his brother.