Imam Ahmad bin Mani' (may Allah have mercy on him) states that Rawh narrated to us; he said: Ibn Jurayj informed us through Ibn Abi Mulaykah, who narrates from a man of Banu Tamim whom we do not accuse of lying (that is, he is trustworthy and reliable). He said: I told the Mother of the Believers, Sayyidah Aishah (may Allah be pleased with her), that Sayyiduna Abdullah bin Umar (may Allah be pleased with them both) says that the Messenger of Allah (peace and blessings be upon him) said: "A month is twenty-nine days." Sayyidah Aishah (may Allah be pleased with her) objected to this and said: 'Yaghfirullahu li-Abi Abd al-Rahman' (May Allah Almighty forgive Abu Abd al-Rahman, that is, Ibn Umar). The Messenger of Allah (peace and blessings be upon him) did not say it like that (absolutely); rather, what he (peace and blessings be upon him) said was: "A month (sometimes) is twenty-nine days."
Explanation: According to the commentators of hadith, Sayyidah Aishah (may Allah be pleased with her) intended to make clear that a month is not always twenty-nine days; rather, depending on the sighting of the crescent, it is sometimes thirty and sometimes twenty-nine days, and she corrected the categorical manner of expression reported by Sayyiduna Ibn Umar (may Allah be pleased with them both).
Hadith Referenceالمطالب العالية بزوائد المسانيد الثمانية / كتاب الصيام / 994
Hadith Gradingمحدثین:إسناده ضعيف
Hadith Takhrij«حکم الحدیث المطالب العالیہ محققاً تنسیق د. سعد بن ناصر بن عبد العزيز الشَّثري- مکتبہ شاملہ :إسناده ضعيف. » «أخرجه صحيح مسلم برقم: 1083، 1475، وأخرجه سنن النسائي برقم: 2131، وأخرجه سنن ابن ماجه برقم: 2059، وأخرجه مسند أحمد برقم: 25536، وأخرجه فتح الباري برقم: 89، 4314، 4509، 4627، 4629، 5874، وأخرجه مسند البزار برقم: 160، 206، وأخرجه مصنف عبد الرزاق برقم: 19497، وأخرجه المعجم الأوسط للطبراني برقم: 1356، 3285، 3547، 3904، 6068، 7100، 8900، وأخرجه إتحاف الخيرة المهرة بزوائد المسانيد العشرة برقم: 2179»