كتاب الإمارة
33  
The Book on Government
(22)
Chapter: Oath of allegiance pledging to hear and obey as much as possible
(22)
باب الْبَيْعَةِ عَلَى السَّمْعِ وَالطَّاعَةِ فِيمَا اسْتَطَاعَ ‏‏
Sahih Muslim 1867

It has been narrated on the authority of Abdullah b. 'Umar who said:

We used to take oath to the Messenger of Allah (ﷺ) that we would listen to and obey his orders. He would tell us (to say in the oath): As far as it lies in my power.
حَدَّثَنَا يَحْيَى بْنُ أَيُّوبَ، وَقُتَيْبَةُ، وَابْنُ، حُجْرٍ - وَاللَّفْظُ لاِبْنِ أَيُّوبَ - قَالُوا حَدَّثَنَا إِسْمَاعِيلُ، - وَهُوَ ابْنُ جَعْفَرٍ - أَخْبَرَنِي عَبْدُ اللَّهِ بْنُ دِينَارٍ، أَنَّهُ سَمِعَ عَبْدَ اللَّهِ بْنَ عُمَرَ، يَقُولُ كُنَّا نُبَايِعُ رَسُولَ اللَّهِ صلى الله عليه وسلم عَلَى السَّمْعِ وَالطَّاعَةِ يَقُولُ لَنَا ‏ "‏ فِيمَا اسْتَطَعْتَ ‏"‏ ‏.‏
Reference : Sahih Muslim 1867
In-book reference : Book 33, Hadith 132
USC-MSA web (English) reference : Book 20, Hadith 4604
  (deprecated numbering scheme)