Hibban bin al-Harith says: I came to Sayyiduna Ali bin Abi Talib (may Allah be pleased with him) while he was encamped with the army at Dayr Abi Musa. I found him eating, and he said: Come near and eat. I said: I intend to fast. He said: I too intended to fast. When he had finished his food, he said to Ibn al-Tayyah: Give the iqamah for the prayer.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 1796