Charles Spurgeon Commentary Matthew 3:7

"But when he saw many of the Pharisees and Sadducees coming to his baptism, he said unto them, Ye offspring of vipers, who warned you to flee from the wrath to come?" — Matthew 3:7 (ASV)

It was strange to see the proud Separatists and the skeptical Moralists come to be baptized, and therefore, as a test, John addressed them with scorching words. He saw that they were serpentine in their motives and viperish in their tempers, and so he calls them, progeny of vipers. Thus, he would see whether they were sincere or not. He asks who suggested to them to flee from that wrath, of which he was the forerunner according to the closing words of the Old Testament.

This inquiry was not complimentary, but it is not the business of the Lord's servants to make themselves pleasing. They must be faithful, and especially so to the great and learned. John the Baptist was faithful in this way, and he was honored for it by the One who sent him.