Numbers 21:6-9

⁶Wherefore the Lord sent among the people fiery serpents, which bit them and killed many of them.a

⁷Upon which they came to Moses, and said: We have sinned, because we have spoken against the Lord and thee: pray that he may take away these serpents from us. And Moses prayed for the people.

⁸And the Lord said to him: Make brazen serpent, and set it up for a sign: whosoever being struck shall look on it, shall live.b

⁹Moses therefore made a brazen serpent, and set it up for a sign: which when they that were bitten looked upon, they were healed.c