Hadith 518000
Chapter 56: Speech - كتاب الكلام
حَدَّثَنِي مَالِكٌ، عَنْ زَيْدِ بْنِ أَسْلَمَ، عَنْ عَبْدِ اللَّهِ بْنِ عُمَرَ، أَنَّهُ قَالَ قَدِمَ رَجُلاَنِ مِنَ الْمَشْرِقِ فَخَطَبَا فَعَجِبَ النَّاسُ لِبَيَانِهِمَا فَقَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم " إِنَّ مِنَ الْبَيَانِ لَسِحْرًا " . أَوْ قَالَ " إِنَّ بَعْضَ الْبَيَانِ لَسِحْرٌ " .
Malik related to me from Zayd ibn Aslam that Abdullah ibn Umar said, "Two men from the east stood up and spoke, and people were amazed at their eloquence. The Messenger of Allah, may Allah bless him and grant him peace, said, 'Some eloquence is sorcery,' or he said, 'Part of eloquence is sorcery.' "
Reference Muwatta Malik 518000
USC-MSA web (English) reference : Book 56, Hadith 7