The Mabinogeon by Thomas Bulfinch

All that day they journeyed until the evening, and then they beheld a vast castle, which was the largest in the world. And lo! a black man, larger than three of the men of this world, came out from the castle. And they spoke unto him, and said, "O man, whose castle is that? " "Stupid are ye, truly, O men! There is no one in the world that does not know that this is the castle of Gwernach the Giant. " "What treatment is there for guests and strangers that alight in that castle? " "O chieftain, Heaven protect thee! No guests ever returned thence alive, and no one may enter therein unless he brings with him his craft."

Then they proceeded towards the gate. Said Gurhyr Gwalstat, "Is there a porter? " "There is; wherefore dost thou call? " "Open the gate. " "I will not open it. " "Wherefore wilt thou not? " "The knife is in the meat, and the drink is in the horn, and there is revelry in the hall of Gwernach the Giant; and except for a craftsman who brings his craft, the gate will not be opened tonight. " "Verily, porter," then said Kay, "my craft bring I with me. " "What is thy craft? " "The best burnisher of swords am I in the world. " "I will go and tell this unto Gwernach the Giant, and I will bring thee an answer."