Sunan an-Nasa'i 660
سنن النسائي#660Sahihأَخْبَرَنَا إِسْحَاقُ بْنُ إِبْرَاهِيمَ، عَنْ وَكِيعٍ، قَالَ حَدَّثَنَا ابْنُ أَبِي ذِئْبٍ، عَنِ الزُّهْرِيِّ، عَنْ سَالِمٍ، عَنْ أَبِيهِ، أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم جَمَعَ بَيْنَهُمَا بِالْمُزْدَلِفَةِ صَلَّى كُلَّ وَاحِدَةٍ مِنْهُمَا بِإِقَامَةٍ وَلَمْ يَتَطَوَّعْ قَبْلَ وَاحِدَةٍ مِنْهُمَا وَلاَ بَعْدُ .
It was narrated from Salim, from his father, that the Prophet (S.A.W) joined them (Maghrib and 'Isha') in Al-Muzdalifah, and he prayed each of them with an Iqamah, and he did not offer any voluntary prayer before or after either of them
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:
In-book reference: 7:35