Jewish law often operates on the derash level of the Bible rather than a simple reading. However, sometimes peshat intersects law in surprising places. I came across such an occurrence in last week’s Torah portion and after some investigation found proper sources affirming my reading.
After God created Chavah, the Torah declares:
על כן יעזב איש את אביו ואת אמו ודבק באשתו והיו לבשר אחד.
Therefore shall a man leave his father and his mother, and shall cleave to his wife, and they shall be one flesh.
The meaning of the term “one flesh” (basar echad) is unclear. Rashi explains it as a resulting child from the couple. Others read it as either physical or spiritual bonding. R. Michael Samuel, in his fascinating psychological-theological-peshat commentary Birth and Rebirth through Genesis, quotes the Christian exegete Gordon Wenham as taking a different approach. Comparing the phrase “one flesh” to the laws of forbidden relationships (Lev. 18, 20) where “flesh” (she’er basar) is used to denote a relative, Wenham explains that a husband and wife become physically related:
[I]t affirms that just as blood relations are one’s flesh and bone, so marriage creates a similar kinship relation between man and wife.” (Word Biblical Commentary, Genesis vol. 1 p. 71).
In other words, this is a legal rather than social or psychological text; it teaches a halakhah about family connections. I found that the Vilna Gaon (Aderes Eliyahu, ad loc.) explains similarly:
והיו לבשר אחד לענין קרבות משפחה כמו כי אחינו בשרנו הוא אל כל שאר בשר. שקרובי אשתו פסולים עליו כקרובי עצמו.
“And they shall be one flesh” regarding family relations. Like “He is our brother, our flesh” (Gen. 37:27) and “to any that is near of kin to him” (Lev. 18:6). [Teaching] that the relatives of his wife are invalid [as witnesses] to him like his own relatives.
However, I think we can take this one step further. Becoming “one flesh” is becoming more than just close relatives; it is becoming the same relative. While this passage teaches that husband and wife become blood relatives, it also teaches that they are equivalent to each other. In other words, this is the source to the rule that “ishto ke-gufo” — his wife is like himself, that husband and wife can fill in for each other in some legal roles, that they grant each other rights such as that of eating the priestly foods, that they treat each other halakhically as themselves. They are legally considered “one flesh.”
Shadal (ad loc.) comes close to saying this: “They cleave to each other so much that they are as if made of one body.” I was delighted to eventually find that the Revid Ha-Zahav (Bereishis, sv. ve-hayu) says precisely this:
פשוט הא דאמרי׳ אשתו כגופו מכאן הוא…
It is clear that that which we say “his wife is like himself” is from here…
The Revid Ha-Zahav continues to explore how literally this rule is taken and whether it applies in reverse (see this post: link). It seems to me that this rule has solid basis in the simple reading of the verse, similar to the explanations of Shadal, the Vilna Gaon and (le-havdil) Wenham.