The Islamic Personality by Sheikh Taqīuddīn An-Nabahānī

The conflict between the actions of the Messenger of Allah (SAW) is not imaginable, because the conflict between two matters is their opposition in a manner that every one of them prevents its opponent. This conflict between two of the Messenger's actions so that one of them abrogates or specifies the other is not imaginable to occur, because if their verdicts do not contradict; there is no conflict between them, and so if the verdicts of the actions contradict; also there is no conflict, because it is possible that the action is waajib at a time, and contrary to it at the similar time without invalidating the verdict of the first one, because the actions have no generality; unlike the sayings. Indeed, if the first action is accompanied with a saying that necessitates the obligation of the repetition, then the second action would be an invalidator or a specifier for that saying not for the action. So basically, the conflict between the two actions is not imaginable. As for the reason why the conflict is not imaginable, that is because the two conflicted actions are either of the similar to each other like the action of the Dthuhr prayer at two similar or different times, or the conflicted actions are of the different to each other. As for the two similar; being not conflicted is apparent in them, that is like praying the Dthuhr prayer at two different times. And as for the two different actions, if their gathering is permissible like the prayer and the fasting; it is also apparent that they are not in conflict. And if the actions are of that which is impossible to imagine their gathering, and their verdicts do not contradict like the Dthuhr and the 'Asr prayers; also there is no conflict between them for the possibility of the gathering, so it is possible to gather the prayer and the fasting, and it is possible to gather the Dthuhr prayer and the 'Asr prayer. And if the actions are of that which is impossible to imagine their gathering and their verdicts are different, like the fasting on a certain day and braking the fasting on another day; also there is no conflict between them, for the occurrence of the obligation at one time and the permissibility at another time, i.e. the action could be waajib or mandoob or mubaah at a time, and differently at another time, and none of them removes or invalidates the verdict of the other, since there is no generality in the two actions, neither in one of them.