Sayyiduna Salim bin Abdullah (may Allah have mercy on him) says that the people saw the new moon of Eid al-Fitr in the daytime, so Abdullah bin Umar (may Allah be pleased with him) completed his fast until night, and said: "No, not until it is seen from where it is seen at night."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصيام / 7986