John Gills Exposition of the Bible Commentary - Genesis 21:4
And Abraham circumcised his son Isaac, being eight days old as , God had commanded him. Genesis 17:12 , and was the first that we read of that was circumcised on that day, according to the divine precept, which Abraham strictly observed; for though this was the son of the promise, and of his old age, for whom he had the most affectionate regard, yet he administered this bloody ordinance on him; nor did he defer it beyond the time, and was himself the operator, as it seems; all which... read more
Matthew Henry's Complete Commentary - Genesis 21:1-8
Few under the Old Testament were brought into the world with such expectation as Isaac was, not for the sake of any great person eminence at which he was to arrive, but because he was to be, in this very thing, a type of Christ, that seed which the holy God had so long promised and holy men so long expected. In this account of the first days of Isaac we may observe, I. The fulfilling of God's promise in the conception and birth of Isaac, Gen. 21:1, 2. Note, God's providences look best and... read more