"We used to pledge to the Messenger of Allah to hear and obey, the he said: 'In as much as you can."' (Using translation from Nasāʾī 4187)
كُنَّا نُبَايِعُ رَسُولَ اللهِ ﷺ عَلَى السَّمْعِ وَالطَّاعَةِ ثُمَّ يَقُولُ «فِيمَا اسْتَطَعْتَ» وَقَالَ عَلِيٌّ «فِيمَا اسْتَطَعْتُمْ»