Matthew 23:2 - Ellicott's Commentary On The Whole Bible

The scribes and the Pharisees sit in Moses’ seat. — The words were probably spoken of their collective action as represented in the Sanhedrin, rather than of their individual work as interpreters of the Law. As such, they claimed to be the authoritative exponents of the Law, and our Lord recognises (unless we suppose a latent protest in His words, like that which is veiled in the “full well ye reject” of Mark 7:9) their official claim to reverence.