War-Gods of the Void by Henry Kuttner

Dying is an uncomfortable business, unless a man is drugged or insensible. Vanning found it so. Moreover, he wasn't the sort of man who would give up without good cause. Weak as he was, nevertheless he was still too strong to lie in the dark, waiting.

Laboriously, he got to his hands and knees and commenced a circuit of the pit. He expected nothing. But, at the southern end of his prison, he was astounded to find a hole in the wall easily large enough to admit his body.