There is a rock underneath the bridge you jump across to reach the bugbear battle In the beginning of the game. It states that you've found something, the rock becomes lit-up but attempting to move the rock it states there is not enough room and that "it's too far"
As far as I remember, there is a strength potion at one of the skeletons under that bridge. Try that potion, and you will be able to move that rock far enough
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