Is it permissible to adopt the dissenting opinion of scholars concerning the issue of following a mujtahid (independent jurist) and abandoning his ruling after acting upon the fatwa, and what is Ibn Taymiyyah's view on that?

The issue is a matter of disagreement and detailed discussion among scholars, and what has been narrated about a consensus on it is either incorrect or applies to a specific situation: that of moving from one madhhab (school of thought) to another merely out of personal desire for a worldly gain, as opposed to returning to a belief based on what is considered stronger or correct and in accordance with legitimate religious evidences.

Al-Amidi said: Scholars have agreed that if a layperson follows a mujtahid (independent jurist) regarding a new ruling and acts upon his opinion, he is not permitted to retract from it in that specific ruling. They differed, however, on whether he can do so in another ruling. Some prohibited it, while others permitted it, and the latter is the correct view. They also differed on whether, if a layperson committed to a specific madhhab, it is permissible for him to adopt the opinion of another in a particular issue. Some allowed it, while others forbade it. The preferred view is to differentiate: for any issue a layperson has acted upon, he should not imitate another. But for an issue he has not acted upon, there is no impediment to following another.

Ibn Amir al-Hajj al-Halabi said: A muqallid (follower of a madhhab) does not retract from what he has imitated a mujtahid in and acted upon, by agreement. This is what Al-Amidi and Ibn al-Hajib held. However, Al-Zarkashi said: It is not as they stated; rather, the disagreement extends even after action. How can it be prevented if one believes in its correctness? Among those who permitted retracting from taqlid (imitation) after acting upon it are Al-Izz ibn Abd al-Salam and Al-Nawawi.

Ibn Hajar al-Haytami said: It is permissible to switch (madhhabs) absolutely. This is what Al-Izz ibn Abd al-Salam ruled, and it is implied by Al-Nawawi’s words. In his collection, he explicitly stated that what is covered by the general statements of the companions regarding a narrated ruling should not be disregarded due to some of them dissenting.

It is stated in the marginalia of Radd al-Muhtar: If someone prayed one day according to a madhhab, and wished to pray another day according to a different one, he is not prevented from it. Therefore, a person is not obliged to adhere to a specific madhhab, and it is permissible for him to act in a way that contradicts what he did according to his madhhab, imitating another imam, provided he meets its conditions. He may act according to two contradictory matters in two incidents that have no connection to each other. However, he is not permitted to invalidate the very action he performed by imitating another imam, because the execution of an act is not to be rescinded.

Among those who held that it is not permissible to imitate another scholar in the same issue after acting upon it is Ibn Mulla Farrokh, who said: One does not retract from taqlid after acting, meaning after what has been done has passed. However, if that incident occurs a second time, he may adopt the opinion of another imam, and there is no impediment to it.

As for Shaykh al-Islam Ibn Taymiyyah, he said: Whoever commits to a specific madhhab, then acts contrary to it without imitating another scholar who issued him a fatwa, nor basing it on evidence that necessitates the contrary, and without a legitimate excuse that permits what he did, then he is following his whims, and this is reprehensible. However, if it becomes clear to him what necessitates the superiority of one opinion over another, either by detailed evidence or by seeing one of two men more knowledgeable in that issue than the other, and he is more God-fearing in what he says, then he moves from one opinion to another for such a reason; this is permissible, rather, obligatory.