Paul now starts his argument from the Law. It says is literally “it is written,” a well-known authoritative formula used traditionally to introduce a quotation from scripture. What follows, however, is not a direct quotation but a summary statement. It says may be rendered in some languages as “in the Law one may read,” or “in the Law are the words about.”

Paul’s illustration is again taken from Abraham, this time concentrating on his two sons, Isaac and Ishmael, a story familiar to every Jewish child and which Jewish preachers often used to prove the superiority of their nation to those outside the covenant. The mothers are not at first referred to by name but are described according to status. The slave woman is, of course, Hagar. The word for slave woman properly means a young woman, but by Paul’s time it had come to mean a servant or a slave. The free woman is Sarah; free here is in antithesis to slave. The Old Testament account referred to is found in chapters 16, 17, and 21 of Genesis.

The statements one by a slave woman, the other by a free woman may be translated as “a woman who was a slave gave birth to one of his sons, and a free woman gave birth to the other.” However, in a number of languages a literal rendering of free woman would be quite misleading, for it would tend to designate a woman who was not married, suggesting a prostitute or a paramour. It may therefore be necessary to say “his wife who was, of course, not a slave.” It may also be important to indicate that the slave woman was a slave of his wife, and one may translate “a woman who was his wife’s slave gave birth to one of his sons, and his wife gave birth to the other.”

Quoted with permission from Arichea, Daniel C. and Nida, Eugene A. A Handbook on Paul’s Letter to the Galatians. (UBS Handbook Series). New York: UBS, 1976. For this and other handbooks for translators see here .