Adam Clarke's Commentary on the Bible - Genesis 18:10
I will certainly return - Abraham was now ninety-nine years of age, and this promise was fulfilled when he was a hundred; so that the phrase according to the time of life must mean either a complete year, or nine months from the present time, the ordinary time of pregnancy. Taken in this latter sense, Abraham was now in the ninety-ninth year of his age, and Isaac was born when he was in his hundredth year. read more
John Gills Exposition of the Bible Commentary - Genesis 18:17
And the Lord said ,.... Either unto Abraham himself, so leading on to what he was about to make known to him; and without supposing this it will be difficult to account for Abraham's intercession for Sodom upon this: or to the two angels with him; not as consulting them whether he should or no do what he next suggests, but to give to them Abraham's just character, and the reasons of his using him in such a friendly manner: or it may be, to the other divine Persons, the Father and Spirit, one... read more