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.  

أَنَّهُ سَمِعَ عَبْدَ اللَّهِ بْنَ عُمَرَ يَقُولُ كُنَّا نُبَايِعُ رَسُولَ اللَّهِ ﷺ عَلَى السَّمْعِ وَالطَّاعَةِ يَقُولُ لَنَا فِيمَا اسْتَطَعْتَ