´It was narrated from Abu Hurairah that the Messenger of allah sadi:` "When you see the crescent then fast, and when you crescent then fast, and when you see it, stop fasting. If it is obscured from you (too cloudy), then fast thirty days."
Hadith ReferenceSunan an-Nasa'i / The Book of Fasting / Hadith: 2121
Hadith Gradingالألبانی:صحيح | زبیر علی زئی:صحيح مسلم
Hadith Takhrij«صحیح مسلم/ الصوم 2 (1081)، سنن ابن ماجہ/الصوم 7 (1655)، (تحفة الأشراف: 13102) ، مسند احمد 2/263، 281 (صحیح)»