Adam Clarke on John 11:38

It was a cave, etc. - It is likely that several of the Jewish burying-places were made in the sides of rocks; some were probably dug down like a well from the upper surface, and then hollowed under into niches, and a flat stone, laid down upon the top, would serve for a door. Yet, from what the evangelist says, there seems to have been something peculiar in the formation of this tomb. It might have been a natural grotto, or dug in the side of a rock or hill, and the lower part of the door level with the ground, or how could Lazarus have come forth, as he is said to have done, Joh 11:44?