The purpose of the levirate marriage ordinance was to enable a man who died before fathering an heir to obtain one and so perpetuate his name and estate. "Levirate"comes from the Latin word levirmeaning husband's brother.
"The practice was common in the patriarchal period [cf. Gen. 38:1-10]. . . . Presumably the prohibition of sexual union with a brother's wife in Leviticus 18:16 and 20:21 refers to such an act while the brother is still living."279
"The taking off of the shoe was an ancient custom in Israel, adopted, according to Ruth iv. 7, in cases of redemption and exchange, for the purpose of confirming commercial transactions. The usage arose from the fact, that when any one took possession of landed property he did so by treading upon the soil, and asserting his right of possession by standing upon it in his shoes [cf. e.g., Gen. 13:17]. In this way the taking off of the shoe and handing it to another became a symbol of the renunciation of a man's position and property. . . . But the custom was an ignominious one in such a case as this, when the shoe was publicly taken off the foot of the brother-in-law by the widow whom he refused to marry. He was thus deprived of the position which he ought to have occupied in relation to her and to his deceased brother, or to his paternal house; and the disgrace involved in this was still further heightened by the fact that his sister-in-law spat in his face."280
The Israelites were to practice levirate marriage only in cases where the brothers had lived together (v. 5) and the remaining brother was not already married. Living together meant sharing the same estate, not necessarily residing under the same roof. When another kinsman voluntarily assumed the responsibility of the surviving brother, that brother was apparently under no obligation to marry his sister-in-law (cf. Ruth 4).
There were several reasons for this provision. These reasons were the importance of descendants in God's purposes for Israel, the welfare of the widow, and the demonstration of love for one's brother (cf. Gen. 38).281
