Galatians 4:23
23But one, the son by the slave woman, was born by natural descent, ▼▼ Grk “born according to the flesh”; BDAG 916 s.v. σάρξ 4 has “Of natural descent τὰ τέκνα τῆς σαρκός
children by natural descent Ro 9:8 (opp. τὰ τέκνα τῆς ἐπαγγελίας). ὁ μὲν ἐκ τῆς παιδίσκης κατὰ σάρκα γεγέννηται
Gal 4:23; cp. vs.
29.”
while the other, the son by the free woman, was born through the promise.