Midrasch zu Jeschijahu 30:6

It also says (in Is. 30:6): VIPER AND FLYING SERPENT. What is the meaning of FLYING SERPENT (saraf, rt.: SRP)?⁵⁸The root, SRP, means “burn.” Whatever the bird flew over was immediately burned (rt.: SRP). R. Hiyya the Great said: There was a certain person in the land of Israel named Merutah.⁵⁹The name means “It Was Plucked.” Why was his name called Merutah? They said: One time he went up to gather wood from the mountains and saw the serpent asleep, but the serpent did not see him. Then his hair fell out from fear. So they called him Merutah, and no hair grew on him until the day of his death. Ergo (in Deut. 8:10): WHO LED YOU….

It is related that while King Shapur (of Persia) was passing through that place with the members of his family, a serpent swallowed one of them. As he continued along, a second member of his family was swallowed up and then a third. King Shapur was deeply saddened, but he did not know what to do. His counselors advised him: “Summon ten mighty men to fill the place with a layer of straw.” He summoned them and they did so. They placed straw around the serpent, and he swallowed it. Then they placed more straw around him, and he swallowed it as well. This continued until his belly swelled up, and they killed him. Hence, Who led thee through the great and dreadful wilderness, wherein were serpents, fiery serpents, and scorpions, and thirsty ground where was no water; who brought thee forth water out of the rock of flint (Deut. 8:15). It says also: The burden of the beasts of the south. Through the land of trouble and anguish, from whence come the lioness and the lion, the viper and the flying serpent (Isa. 30:6). The word ef’eh is employed with reference to a viper. They say that when a viper looks at the shadow of a bird flying through the air, the bird immediately becomes entranced and falls apart. Nevertheless, they did not say: Where is the Lord that brought us 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 (Jer. 2:6). What is meant by the word tzalmavet (“shadow of death”)? A place where there is tzal (“shadow”) accompanied by mavet (“death”).