Deuteronomy 24:19

24:19 Whenever you reap your harvest in your field and leave some unraked grain there, you must not return to get it; it should go to the resident foreigner, orphan, and widow so that the Lord your God may bless all the work you do.

Deuteronomy 25:7

25:7 But if the man does not want to marry his brother’s widow, then she must go to the elders at the town gate and say, “My husband’s brother refuses to preserve his brother’s name in Israel; he is unwilling to perform the duty of a brother-in-law to me!”