Sunan an-Nasa'i 1149
سنن النسائي#1149Sahihأَخْبَرَنَا قُتَيْبَةُ، قَالَ حَدَّثَنَا أَبُو الأَحْوَصِ، عَنْ أَبِي إِسْحَاقَ، عَنْ عَبْدِ الرَّحْمَنِ بْنِ الأَسْوَدِ، عَنِ الأَسْوَدِ، وَعَلْقَمَةَ، عَنْ عَبْدِ اللَّهِ، قَالَ كَانَ رَسُولُ اللَّهِ صلى الله عليه وسلم يُكَبِّرُ فِي كُلِّ رَفْعٍ وَوَضْعٍ وَقِيَامٍ وَقُعُودٍ وَأَبُو بَكْرٍ وَعُمَرُ وَعُثْمَانُ رضى الله عنهم .
It was narrated that Abdullah said:"The Messenger of Allah (ﷺ) used to say the takbir every time he got up, went down, stood and sat. Abu Bakr, 'Umar, and 'Uthman (did likewise)
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: 12:121