The Book of The At-Tatbiq (Clasping One's Hands Together)
12/90. Chapter:
The takbir for the prostration
Sunan an-Nasai
أَخْبَرَنَا 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)."
Reference : Sunan an-Nasa'i 1149In-book reference : Book 12, Hadith 121English translation : Vol. 2, Book 12, Hadith 1150