صحیح ابن حبان
Ibn Hibban
كتاب الصوم
Book of Fasting
فصل في صوم يوم الشك - ذكر الزجر عن أن يصوم المرء اليوم الذي يشك فيه أمن شعبان أم من رمضان
Section on Fasting the Day of Doubt - Warning against fasting the day of doubt, whether it is Sha’ban or Ramadan
1 hadith
Hadith 3593
Sayyiduna Abdullah bin Umar, may Allah be pleased with them both, narrates this statement of the Noble Prophet, peace and blessings be upon him: "The month can also be of twenty-nine days. Do not begin fasting until you see (the new moon), and do not celebrate Eid al-Fitr until you see it. And if the sky is overcast, then complete the counting."