الكافي- ط الاسلامية, volume 7, page 448

2. Muhammad ibn Yahya has narrated from Ahmad ibn Muhammad and Ali ibn Ibrahim has narrated from his father all from ibn Mahbub from abu Ja‘far al-Ahwal from Salam ibn al-Mustanir who has narrated the following: “This is about the meaning of the words of Allah, most Majestic, most Glorious. ‘. . . We made a covenant with Adam (a.s.), before but he forgot and We did not find in him firm determination.’ (20:115) Abu Ja‘far (a.s.), has said, ‘When Allah, most Majestic, most Glorious, said to Adam (a.s.), to enter in the garden (paradises) He said, “O Adam, you must not go near this tree.’” He (the Imam) said that He showed it to him and Adam said to his Lord, “How will I go near the tree when You have prohibited me and my wife?” He (the Imam) said that Allah said to them not to go near the tree meaning do not eat thereof. Adam and his wife said, “Yes, Lord we will not go near the tree and will not eat”, but they did not make an exception (did not say, ‘if Allah wills’) when saying, “yes” Allah, in that matter left them on their own and to their memories.’ He (the Imam) said, ‘Allah, most Majestic, most Glorious, spoke to His Holy Prophet, O Allah, grant compensation to Muhammad and his family worthy of their services to Your cause, about a fact in the book. “. . . You must never say about anything, ‘I will do it tomorrow without saying, ‘unless Allah wills’ otherwise,” (18:23) and Allah decides that I must not do then I will not be able to do.’ He (the Imam) said that for this reason Allah, most Majestic, most Glorious, has said, ‘. . . you must speak of your Lord when you forget’, meaning make the act and the will of Allah an exception in your act.’”

Translation: Muhammad Sarwar — attributed by Thaqalayn·The Arabic above is the original.