'Shadow of Death' in the Bible

Neither said they, Where is Jehovah that brought us up out of the land of Egypt, that led us through the wilderness, through a land of deserts and of pits, through a land of drought and of the shadow of death, through a land that none passed through, and where no man dwelt?

Give glory to Jehovah your God, before he cause darkness, and before your feet stumble upon the dark mountains, and, while ye look for light, he turn it into the shadow of death, and make it gross darkness.