John Gills Exposition of the Bible Commentary - Genesis 16:16
And Abram was eighty years old when Hagar bare Ishmael to Abram. Which is easily reckoned, for he was seventy five years of age when he left Haran, Genesis 12:4 ; and he had been ten years in Canaan when Hagar was given him by Sarai for his wife, Genesis 16:3 ; and so must be then eighty five years of age, and of course must be eighty six when Ishmael was born. read more
Matthew Henry's Complete Commentary - Genesis 16:15-16
It is here taken for granted, though not expressly recorded, that Hagar did as the angel commanded her, returning to her mistress and submitting herself; and then, in the fulness of time, she brought forth her son. Note, Those who obey divine precepts shall have the comfort of divine promises. This was the son of the bond-woman that was born after the flesh (Gal. 4:23), representing the unbelieving Jews, Gal. 4:25. Note, 1. Many who can call Abraham father are 608 yet born after the flesh,... read more