Sunan Abi Dawud 1295
سنن أبي داود#1295Sahihحَدَّثَنَا عَمْرُو بْنُ مَرْزُوقٍ، أَخْبَرَنَا شُعْبَةُ، عَنْ يَعْلَى بْنِ عَطَاءٍ، عَنْ عَلِيِّ بْنِ عَبْدِ اللَّهِ الْبَارِقِيِّ، عَنِ ابْنِ عُمَرَ، عَنِ النَّبِيِّ صلى الله عليه وسلم قَالَ " صَلاَةُ اللَّيْلِ وَالنَّهَارِ مَثْنَى مَثْنَى " .
Narrated Abdullah ibn Umar: The Prophet (ﷺ) said: Prayer by night and day should consist of pairs of rak'ahs
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:
Al-AlbaniSahih
Muhammad Muhyi Al-Din Abdul HamidSahih
Shuaib Al ArnautSahih
Zubair Ali ZaiHasan
In-book reference: 5:46