Sahih Muslim
The Book of Prayers (Kitab Al-Salat)
Book Number: 004 / Hadith Number: 867
Jabir b. Samura reported: We said our prayer with the Messenger of Allah (may peace be upon him) and, while pronouncing salutations, we made gestures with our hands (indicating)" Peace be upon you, peace be upon you." The Messenger of Allah (may peace be upon him) looked towards us and said: Why is it that you make gestures with your hands like the tails of headstrong horses? When any one of you pro- nounces salutation (in prayer) he should only turn his face towards his companion and should not make a gesture with his hand.