ייִדישער מחשבֿה אויף בראשית 38:8

The reason of the law concerning marrying the deceased brother’s wife is stated in the Bible (Deut. 25:5). It was a custom in force before the Law was given, and the Law perpetuated it. The ceremony of haliẓah (ibid. 6, seq.), “taking off the shoe,” has been introduced, because in those days it was considered disgraceful to go through that ceremony, and in order to avoid the disgrace, a person might perhaps be induced to marry his deceased brother’s wife. This is evident from the words of the Law: “So shall it be done unto that man that will not build up his brother’s house. And his name shall be called in Israel, The house of him that hath his shoe loosed” (Deut. 25:9).