Sahih Muslim 2516
صحيح مسلم#2516Sahihوَحَدَّثَنَا عُبَيْدُ اللَّهِ بْنُ مُعَاذٍ، حَدَّثَنَا أَبِي، حَدَّثَنَا شُعْبَةُ، عَنْ مُحَمَّدِ بْنِ زِيَادٍ، قَالَ سَمِعْتُ أَبَا هُرَيْرَةَ، - رضى الله عنه - يَقُولُ قَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم " صُومُوا لِرُؤْيَتِهِ وَأَفْطِرُوا لِرُؤْيَتِهِ فَإِنْ غُمِّيَ عَلَيْكُمُ الشَّهْرُ فَعُدُّوا ثَلاَثِينَ " .
Abu Huraira reported Allah's Messenger (ﷺ) as saying:Observe fast on sighting it (the new moon) and break it on sighting it. But if (due to clouds) the actual position of the month is concealed from you, you should then count thirty (days)
Scholarly Authentication
The label above is the grade most of these scholars gave — one dissenting opinion no longer speaks for all of them. If any scholar calls a narration fabricated, that verdict is shown instead, whatever the others say. Each scholar's own wording:
Every narration in Sahih Muslim is accepted as Sahih (authentic) by the established status of the book.
In-book reference: 13:22