Jami` at-Tirmidhi 693

Muhammad bin Abi Harmalah narrated:"Kuraib informed me that Umm Al-Fadl bin Al-Harith sent him to Mu'awiyah in Ash-Sham. He said: 'So I arrived in Ash-Sham and finished her errand, and I saw the crescent of Ramadan while I was in Ash-Sham. We saw the crescent on the night of Friday. Then I arrived in Al-Madinah at the end of the month. Ibn Abbas was questioning me, then he mentioned the crescent and he said: "When did you see the crescent?" I said: "We saw it n the night of Friday." He said: "Did you see it on the night of Friday?" I said: "The people saw it, so they fasted, and Mu'awiyah fasted." He said: "But we saw it on the night of Saturday, so we will not stop fasting until we complete thirty days or we see it." So I said: "Is not the sighting and fasting of Mu'awiyah enough for you?" He said: "This is not how the Messenger of Allah ordered us