'Shadow of Death' in the Bible

Neither did they say, 'Where is Yahweh who brought us up out of the land of Egypt, who 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 lived?'

Give glory to Yahweh your God, before he causes darkness, and before your feet stumble on the dark mountains, and, while you look for light, he turns it into the shadow of death, and makes it gross darkness.