"Many of those who profess to believe the truth would say, if they expressed their real sentiments, What need is there of speaking so plainly? They might as well ask, Why need John the Baptist have said to the Pharisees, “O generation of vipers, who hath warned you to flee from the wrath to come?” [ Matthew 3:7 .] Why need he have provoked the anger of Herodias by telling Herod that it was unlawful for him to live with his brother's wife? He lost his life by speaking so plainly. Why could he not have moved along without incurring the anger of Herodias? GW 149.2"
"But when he saw many of the Pharisees and Sadducees come to his baptism, he said unto them, O generation of vipers, who hath warned you to flee from the wrath to come?"
Ellen White directly references Matthew 3:7 in this passage.