Sayyiduna Ibn Abbas (may Allah be pleased with them both) narrated that when al-Aqra' bin Habis (may Allah be pleased with him) gave a speech, the Prophet (peace and blessings be upon him) interjected in the middle of his speech and said: "Indeed, some eloquence has the effect of magic."
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 12215