Albert Barnes Commentary Mark 7:9

"And he said unto them, Full well do ye reject the commandment of God, that ye may keep your tradition." — Mark 7:9 (ASV)

Full well. These words are capable of different interpretations. Some read them as a question: "Do you do well in rejecting?" and so on. Others suppose they mean skilfully, cunningly. "You show great cunning, or art, in laying aside God's commands and substituting those of men in their place." Others suppose them to be ironical. "How nobly you act! From conscientious attachment to your traditions, you have made void the law of God;" meaning to suggest by this that they had acted wickedly and shamefully.