This day will the Lord deliver thee into mine hands
Of which he was assured by divine inspiration, by the impulse of the Spirit of God upon him; or otherwise he could not have expressed himself with such certainty, and have given the particulars of what he should do, as in the following clauses:
and I will smite thee, and take thine head from thee;
and yet he had no weapon in his hand to do it with, ( 1 Samuel 17:50 ) , but it was revealed to him that he should do it, and he believed it; though the Philistine no doubt looked upon all this as romantic:
and I will give the carcasses of the host of the Philistines this day
unto the fowls of the air, and to the wild beasts of the earth;
not only this man's carcass, which should fall and become a prey to fowls and wild beasts, but the carcasses of the Philistine army, which fleeing upon the fall of their champion, and pursued by the Israelites as they were, would be cut off, and become the food of wild creatures, see ( 1 Samuel 17:52 ) ; though some think the plural is put for the singular, and that it only means his carcass, who was a Philistine; but the host of the Philistines, carries it to the other sense: and this would be done,
that all the earth may know there is a God in Israel;
not only the land of Canaan or Palestine, but the whole earth, and all the inhabitants of it, who should hear of the fall of this giant by such means, and of the rout of the Philistine army upon it; the report of which no doubt was spread far, and near.