It is narrated from Sayyiduna Ibn Umar (may Allah be pleased with them both) that some people came to the Messenger of Allah (peace and blessings be upon him) and spoke, and the people were amazed by (the eloquence of) their speech. Then the Prophet (peace and blessings be upon him) said: "Speak in your (natural) manner, for surely some eloquence is (as powerful as) magic, and hair-splitting in speech (with affectation and artificiality) is from Satan."
Hadith Referenceالمعجم الأوسط / باب الألف / 978
Hadith Takhrij«أخرجه البخاري فى «صحيحه» برقم: 5146، 5767، ومالك فى «الموطأ» برقم: 3614 / 817، وابن حبان فى «صحيحه» برقم: 5718، 5795، وأبو داود فى «سننه» برقم: 5007، والترمذي فى «جامعه» برقم: 2028، وأحمد فى «مسنده» برقم: 4741، 5328، 5387، 5791، وأبو يعلى فى «مسنده» برقم: 5639، 5640»