Tamim bin Tarafah narrates from Sayyiduna Jabir bin Samurah (may Allah be pleased with him): The Prophet (peace and blessings be upon him) entered the mosque and saw that they were raising their hands. He (peace and blessings be upon him) said: "What is the matter with them, that they raise their hands like the tails of unruly horses? Be still in prayer."
Hadith Referenceالمعجم الكبير للطبراني / باب الجيم / 1809