KJV:
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?
NASB:
But when he saw many of the Pharisees and Sadducees coming for baptism, he said to them, "You brood of vipers, who warned you to flee from the wrath to come?
KJV:
O generation of vipers, how can ye, being evil, speak good things? for out of the abundance of the heart the mouth speaketh.
NASB:
"You brood of vipers, how can you, being evil, speak what is good? For the mouth speaks out of that which fills the heart.