Another feature of "biblical marriage" that remains irrelevant today concerns who the people of Yahweh may marry. The ancient Hebrews engaged in endogomous marriages, or marriages within their tribe.
Abraham secured a wife from his family: he married Sarai, his half sister. According to Gen. 20:12, they shared the same father but not the same mother.
Abraham arranged an endogamous marriage for his son Isaac with relatives back in Haran.
" And Abraham was old, and well stricken in age: and the Lord had blessed Abraham in all things. And Abraham said unto his eldest servant of his house, that ruled over all that he had, Put, I pray thee, thy hand under my thigh: And I will make thee swear by the Lord, the God of heaven, and the God of the earth, that thou shalt not take a wife unto my son of the daughters of the Canaanites, among whom I dwell: But thou shalt go unto my country, and to my kindred, and take a wife unto my son Isaac." Gen 24:1-4 (KJV)
Isaac arranged an endogamous marriage with relatives back in Haran:
"And Isaac called Jacob, and blessed him, and charged him, and said unto him, Thou shalt not take a wife of the daughters of Canaan. Arise, go to Padanaram, to the house of Bethuel thy mother's father; and take thee a wife from thence of the daughters of Laban thy mother's brother." Gen 28:1-3 (KJV)
Isaac's brother Esau, in contrast, displeased his parents by marrying outside the tribe:
"And Esau was forty years old when he took to wife Judith the daughter of Beeri the Hittite, and Bashemath the daughter of Elon the Hittite: Which were a grief of mind unto Isaac and to Rebekah." Gen 26:34-35 (KJV)
These well-established cultural practices later evolved into commands from Yahweh to the Hebrews through the Mosaic Law that included the religious basis:
"Neither shalt thou make marriages with them; thy daughter thou shalt not give unto his son, nor his daughter shalt thou take unto thy son.For they will turn away thy son from following me, that they may serve other gods: so will the anger of the Lord be kindled against you, and destroy thee suddenly." Deut 7:3-4 (KJV)
Not sure what to make of this last command, given that Yahweh permits the marriage to foreign women captured in war.