ISB ~ Galatians 3 v16

and to his offspring:A reference to Gen 22:18. I

• Paul is alluding to the covenant oath that God swore to Abraham to bless all nations through Isaac and his descendants (Sir 44:21; CCC 706). It is significant for Paul that Abraham’s other son, Ishmael, was disinherited in the preceding chapter of Genesis and thus excluded from this covenant (Gen 21:1012). Thus, when Paul stresses that the word “offspring” is singular rather than plural, he is (1) alluding to the divine election of Isaac over Ishmael in the Genesis narrative (Gal 4:28-31; Rom 9:7-8) and (2) implying that Isaac is a type of Christ, so that the act that elicits the promised blessing (the sacrifice of Isaac) prefigures the act that fulfills it (the sacrifice of Jesus). See note on Rom 8:32.