A fiery serpent That is, the figure of a serpent in brass, which is of a fiery colour. This would require some time: God would not speedily take off the judgment, because he saw they were not thoroughly humbled. Upon a pole That the people might see it from all parts of the camp, and therefore the pole must be high, and the serpent large. When he looketh This method of cure was prescribed, that it might appear to be God's own work, and not the effect of nature or art: and that it might be an eminent type of our salvation by Christ. The serpent signified Christ, who was in the likeness of sinful flesh, though without sin, as this brazen serpent had the outward shape, but not the inward poison of the other serpents: the pole resembled the cross upon which Christ was lifted up for our salvation: and looking up to it designed our believing in Christ. He lived He was delivered from death, and cured of his disease.
Related Commentaries of Numbers 21:8
Numbers 21:8-9
8 And the LORD said unto Moses, Make thee a fiery serpent, and set it upon a pole: and it shall come to pass, that every one that is bitten, when he looketh upon it, shall live.
9 And Moses made a serpent of brass, and put it upon a pole, and it came to pass, that if a serpent had bitten any man, when he beheld the serpent of brass, he lived.