Jamieson, Fausset and Brown on 1 Samuel 1:12-18

12-18. Eli marked her mouth--The suspicion of the aged priest seems to indicate that the vice of intemperance was neither uncommon nor confined to one sex in those times of disorder. This mistaken impression was immediately removed, and, in the words, "God grant," or rather, "will grant," was followed by an invocation which, as Hannah regarded it in the light of a prophecy pointing to the accomplishment of her earnest desire, dispelled her sadness, and filled her with confident hope [1Sa 1:18]. The character and services of the expected child were sufficiently important to make his birth a fit subject for prophecy.

1Sa 1:20. Samuel Born.