A.T. Robertson Commentary Galatians 4:28

"Now we, brethren, as Isaac was, are children of promise." — Galatians 4:28 (ASV)

Now we (ημεις δε). Some MSS. have υμεις δε (now ye). In either case Paul means that Christians (Jews and Gentiles) are children of the promise as Isaac was (κατα Ισαακ, after the manner of Isaac).