Then said Utgard-Loke: Now I will tell you the truth, since you have come out of the burg, that if I live, and may have my way, you shall never enter it again; and this I know, forsooth, that you should never have come into it had I before known that you were so strong, and that you had come so near bringing us into great misfortune. Know, then, that I have deceived you with illusions.

[...]

In the next place, you struck me three times with the hammer. The first blow was the least, and still it was so severe that it would have been my death if it had hit me. You saw near my burg a mountain cloven at the top into three square dales, of which one was the deepest,—these were the dints made by your hammer. The mountain I brought before the blows without your seeing it.

- Prose Edda (The Fooling of Gylfe, XIV)