18. Muhammad ibn al-Hasan ibn Ahmad ibn al-Walid said: Sa`d ibn `Abd Allah said, on the authority of all three Ahmad ibn Muhammad ibn `Isa; Muhammad ibn `Abd al-Hamid and Muhammad ibn al-Husayn ibn Abu al-Khattab, on the authority of Ahmad ibn Muhammad ibn Abu Nasr, on the authority of some of our scholars that Abu `Abd Allah al-Sadiq said:

“A servant cannot accomplish an action unless Allah, the Mighty and High, has granted him the ability of doing so. Verily, the legal capacity [taklif] from Allah has occurred after the ability. Thus, no one has legal capacity except for the capable.”