Deuteronomy 25:4-6

Young's Literal Translation

⁴ `Thou dost not muzzle an ox in its threshing.

⁵ `When brethren dwell together, and one of them hath died, and hath no son, the wife of the dead is not without to a strange man; her husband's brother doth go in unto her, and hath taken her to him for a wife, and doth perform the duty of her husband's brother;

⁶ and it hath been, the first-born which she beareth doth rise for the name of his dead brother, and his name is not wiped away out of Israel.