Genesis 38:8

“And Judah said unto Onan, etc.] Some time after his brother’s death: go in unto thy brother’s wife, and marry her; Moses here uses a word not common for marriage, but which was peculiar to the marrying of a brother’s wife according to a law given in his time: it appears to have been a custom before, and which the patriarch might be directed to by the Lord, in such a case when a brother died, and left no issue, for the sake of multiplication of seed, according to the divine promise, and which in the time of Moses passed into a law, (see <052505>Deuteronomy 25:5); and raise up seed unto thy brother; that might bear his name, and enjoy his inheritance. For this law or custom was partly…”

“Judah said unto Onan . . . marry her, and raise up seed to thy brother--The first instance of a custom, which was afterwards incorporated among the laws of Moses, that when a husband died leaving a widow, his brother next of age was to marry her, and the issue, if any, was to be served heir to the deceased (compare Deu 25:5).”

“- The Family of Judah 1. עדלם ‛ǎdûllâm, ‘Adullam, “righteousness.” חירה chı̂yrâh Chirah, “nobility?” 2. שׁוּע shûa‛, Shua‘, “luck, riches, cry.” 3. ער ‛êr, ‘Er, “watching.” 4. אונן 'ônân, Onan, “strong.” 5. שׁלה shēlâh, Shelah, “request? rest.” כזיב kezı̂yb Kezib, “falsehood.” 6. תמר tāmār, Tamar, “palm.” 12. תמנה tı̂mnâh, Timnah, “counted or assigned.” 14. עינים 'êynayı̂m, ‘Enaim, “two fountains.” 29. פרץ perets, Perets, “breach.” This strange narrative is an episode in the history of Joseph; but an integral part of the “generations” of Jacob. It is loosely dated with the phrase “at that time.” This does not indicate a sequel to the preceding record, the proper phrase for…”

“38:8 as our law requires. . . . You must produce an heir for your brother: The custom that informs this episode is the law for levirate marriage (Latin levir, “husband’s brother”). By this custom, which was later incorporated into God’s law for Israel (Deut 25:5-10), if a man died childless, his brother or nearest relative would marry his widow to produce a child who would carry on the family name of the deceased and inherit his property. Apparently, the near kinsman had a right to refuse, but he would be disgraced in the family for refusing to perpetuate his brother’s name.”