Deuteronomy 25:5

Then the firstborn said to the younger, “Our father is old, and there is not a man on earth to come in to us after the manner of the earth.

Then Judah said to Onan, “Go in to your brother’s wife, and perform your duty as a brother-in-law to her, and raise up a seed for your brother.”

But Naomi said, “Return, my daughters. Why should you go with me? Have I yet sons in my womb, that they may be your husbands?

“And now, is not Boaz our kinsman, with whose young women you were? Behold, he is winnowing barley at the threshing floor tonight.

“Stay this night, and it will be in the morning that, if he will redeem you, good; let him redeem you. But if he does not desire to redeem you, then I will redeem you, as Yahweh lives. Lie down until morning.”

Then Boaz said, “On the day you acquire the field from the hand of Naomi, you must also acquire Ruth the Moabitess, the widow of the one who had died, in order to raise up the name of the one who had died, on behalf of his inheritance.”

saying, “Teacher, Moses said, ‘If a man dies having no children, his brother as next of kin shall marry his wife and raise up a seed for his brother.’

“Teacher, Moses wrote for us that if a man’s brother dies and leaves behind a wife and leaves no child, his brother should marry the wife and raise up a seed for his brother.

and they questioned Him, saying, “Teacher, Moses wrote for us that if a man’s brother dies, having a wife, and he is childless, his brother should marry the wife and raise up seed for his brother.