Deuteronomy 25:6

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.”

And Onan knew that the seed would not be his; and it happened that when he went in to his brother’s wife, he wasted it on the ground in order not to give seed to his brother.

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

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.”

“And also, I have acquired Ruth the Moabitess, the widow of Mahlon, to be my wife in order to raise up the name of the one who had died, on behalf of his inheritance, so that the name of the one who had died will not be cut off from his brothers or from the gate of his birth place; you are witnesses today.”