Matthew only. But if ye had known what this meaneth, I wilt have mercy, and not sacrifice, ye would not have condemned the guiltless (on the quotation, see Matthew 9:13, note). Had you learned the simple Bible truth that God places the exercise of your moral faculties, particularly those of kindness, above merely external observances, you would not have committed this sin of taking up the position of wrong judges.
He traces their error up to its true source, ignorance of the first principles of religion, ignorance of what God really desires. Condemned. Formally and officially ( καταδικάζω). The guiltless. As were the very priests (verse 5).