Boyd’s Bible Dictionary:
(lack). When a married man died without children, his brother, if still living with the family, had a right under the law to marry the widow in order to preserve the family name and inheritance (Deut. 25:5-6; Matt. 22:23-30). Other provisions of the Mosaic law show great consideration for widows (Ex. 22:22; Deut. 14:29; 16:11,14; 24:19-21; 26:12; 27:19).