A summary of the concepts of Ahl al-Sunnah:
Inability to perform an entire command does not waive the obligation to fulfill whatever of it lies within one's capability.
Thus, whoever has had their hand amputated is exempt from washing the hand during wudu,
yet the obligation remains upon them to wash the rest of the arm up to the elbow.
The scholars derived this principle from the words of Allah, the Exalted:
“So keep your duty to Allah as best ye can, and listen, and obey, and spend; that is better for your souls. And whoso is saved from his own greed, such are the successful.” (64:16)
For this is what fearing Allah according to one's capability necessitates.
This is also indicated by his statement, peace and blessings of Allah be upon him:
"When I command you to do something, fulfill as much of it as you are able."
Related by al-Bukhari.
A summary of the concepts of Ahl al-Sunnah: