صحیح ابن حبان
Ibn Hibban
كتاب الصوم
Book of Fasting
فصل في صوم يوم الشك - ذكر الزجر عن أن يتقدم المرء صيام رمضان بصوم يوم أو يومين مبتدأين
Section on Fasting the Day of Doubt - Warning against starting Ramadan by fasting a day or two before it
1 hadith
Hadith 3592
Sayyiduna Abu Hurairah (may Allah be pleased with him) narrates: The Prophet Muhammad (peace and blessings be upon him) said: "Do not begin fasting one or two days before Ramadan, except for a person who (according to some other routine) keeps a fast, then he may fast on that day."