One of the guards of the land of Danes told Beowulf that no one has yet to sleigh Grendel and Beowulf’s response was simply as if saying, do you know who i am? because he knows his strength. With beowulf responding like that it is also similar to when Jesus would be doubted by others and he would respond with a similar type statement because he too knew his power.
Beowulf then decides that he and his men are going trick Grendel into attacking them by playing music and having fun in the hall of heorot. They then lay down and sleep until grendel attacks and is about to grab Beowulf and when he does beowulf fights back and cuts grendel's arm off as a trophy to show that he is not weak and has killed grendel. After Beowulf shows he has won the guard who has doubted him asks for forgiveness which beowulf grants, and everyone knows that is very similar to Jesus have to grant forgiveness to many people. He then hangs Grendel’s arm on the wall of Heorot so that everyone to enter can see that he has defeated the beast (although he is slightly ashamed that he didn’t have more than just an arm as a trophy). With him