Charles Spurgeon Commentary Galatians 4:22-23

"For it is written, that Abraham had two sons, one by the handmaid, and one by the freewoman. Howbeit the [son] by the handmaid is born after the flesh; but the [son] by the freewoman [is born] through promise." — Galatians 4:22-23 (ASV)

For it is written, that Abraham had two sons, the one by a bondmaid, and the other by a freewoman. But he who was of the bondwoman was born after the flesh;

In the strength of Abraham.