Sahih Muslim 1654
صحيح مسلم#1654Sahihحَدَّثَنَا عَبْدُ اللَّهِ بْنُ مَسْلَمَةَ بْنِ قَعْنَبٍ، وَقُتَيْبَةُ بْنُ سَعِيدٍ، قَالاَ حَدَّثَنَا مَالِكٌ، ح وَحَدَّثَنَا يَحْيَى بْنُ يَحْيَى، قَالَ قَرَأْتُ عَلَى مَالِكٍ عَنْ عَامِرِ بْنِ عَبْدِ اللَّهِ بْنِ الزُّبَيْرِ، عَنْ عَمْرِو بْنِ سُلَيْمٍ الزُّرَقِيِّ، عَنْ أَبِي قَتَادَةَ، أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم قَالَ " إِذَا دَخَلَ أَحَدُكُمُ الْمَسْجِدَ فَلْيَرْكَعْ رَكْعَتَيْنِ قَبْلَ أَنْ يَجْلِسَ " .
Abu Qatada (a Companion of the Prophet) reported Allah's Messenger (ﷺ) as saying:When any one of you enters the mosque, he should observe two rak'ahs (of Nafl prayer) before sitting
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: 6:84