A.T. Robertson Commentary Matthew 9:34

"But the Pharisees said, By the prince of the demons casteth he out demons." — Matthew 9:34 (ASV)

By the prince of the devils (εν τω αρχοντ των δαιμονιων). Demons, not devils. The codex Bezae omits this verse, but it is probably genuine. The Pharisees are becoming desperate and, unable to deny the reality of the miracles, they seek to discredit them by trying to connect Jesus with the devil himself, the prince of the demons. They will renew this charge later (Matthew 12:24) when Jesus will refute it with biting sarcasm.