صحیح ابن حبان
Ibn Hibban
كتاب الصوم
Book of Fasting
باب رؤية الهلال - ذكر البيان بأن رؤية هلال شوال إذا غم على الناس كان عليهم إتمام رمضان ثلاثين يوما
Chapter on Sighting the Crescent - Clarifying that if the crescent of Shawwal is obscured, Ramadan should be completed thirty days
1 hadith
Hadith 3457
Sayyiduna Abu Huraira (may Allah be pleased with him) narrates this statement of the Prophet Muhammad (peace and blessings be upon him): "Begin fasting upon sighting it (i.e., the new moon), and celebrate Eid al-Fitr upon sighting it. If the sky is overcast for you, then complete thirty fasts."