Answer: “For I say in sooth, thou son of Ecglaf,, , never had Grendel these grim deeds wrought,, , monster dire, on thy master dear,, , in Heorot such havoc, if heart of thine, , were as battle-bold as thy boast is loud!”
Explanation: He is basically saying that Unferth boasts about his strength but doesn't actually have the skills to match it and that he's exaggerating.