Pri HaAretz
It is written in the Midrash "Taking one of the stones of that place", in the beginning there were many stones and for Jacob they became one stone. And it is therefore said "[Jacob] took the stone" (see there).
Rashi on Genesis
ויפגע במקום AND HE LIGHTED UPON THE PLACE — Scripture does not mention which place, but by writing בַּמָקוֹם the place it refers to the place mentioned already in another passage, viz., Mount Moriah of which it is stated (Genesis 22:4) “And he saw the place (המקום) afar off”.
Rashbam on Genesis
ויפגע במקום, on his way he had an encounter in or near a town known as Luz.