Hadith.68 - The Commander of the Faithful Imam Ali ibn Abi Talib (as), said: "The initiation of prayer is purification (ablution), its prohibition is the takbir (saying 'Allahu Akbar'), and its permissibility is the Tasleem (saying 'Assalamu Alaikum')."

Translation: Bab Ul Qaim Publications·Thaqalayn link·The Arabic above is the original.