Mukhtasar Muslim

`Sayyiduna Abdullah bin Umar (may Allah be pleased with them both) says that` we used to pledge allegiance to the Messenger of Allah (peace and blessings be upon him) to listen and obey, and the Messenger of Allah (peace and blessings be upon him) would say: Say also, "As much as I am able." (This was the compassion of the Prophet, peace and blessings be upon him, for his Ummah, that if something could not be done, they would not be sinful for not doing it.)