Salim (may Allah have mercy on him) says that Sayyiduna Ibn Umar (may Allah be pleased with him) used to say: When people see the new moon in the daytime they break their fast; it is not right for you to break your fast until you see it at night from where it is seen.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصيام / 7987