Some mention the account of `Umar’s position over the difference of opinion that took place between Ubayy ibn Ka`b and `Abd Allah ibn Mas`ud over the matter of praying in a single garment. Ibn `Abd al-Barr said in his book Jami` bayan al-`ilm:
`Umar ibn al-Khattab was angry about the disagreement between Ubayy ibn Ka`b and Ibn Mas`ud on the question of praying in a single cloth: Ubayy said that it was fine and good, while Ibn Mas`ud said that this was done only when clothes were scarce. `Umar said: “Two men disagreeing from among the Prophet’s Companions who are those one looks at and takes from?!” — and this supports the import of the hadith which they have declared weak whereby My Companions are like the stars; whoever among them you use for guidance, you will be rightly guided. `Umar continued: “Ubayy has told the truth, nor has Ibn Mas`ud fallen short of it: but don’t let me hear anyone disagree about this matter after this point, or I will do such-and-such with them!”
`Umar considered neither Ubayy nor Ibn Mas`ud to be wrong, as illustrated by `Umar’s answer in the following hadith from the Book of Prayer in Sahih al-Bukhari:
Narrated Abu Hurayra: A man stood up and asked the Prophet about praying in a single garment. The Prophet said, “Has everyone of you two garments?” A man put a similar question to `Umar whereupon he replied: “When Allah makes you wealthier then you should act wealthier. Let a man gather up his clothes about himself. One can pray in a loinwrap and mantle, or a loinwrap and shirt, or in a loinwrap and long sleeves, or in trousers and a cloak, or in trousers and a shirt, or in trousers and long sleeves, or in legless breeches and long sleeves, or in shorts and a shirt.” The narrator added: “And I think he said: “Or in shorts and a cloak.”
Ibn Hajar in Fath al-Bari relates that the second questioner in the above hadith, that is: the man who asked `Umar, was `Abd Allah ibn Mas`ud. He mentions the report in the Musannaf of `Abd al-Razzaq whereby Ibn Mas`ud approached `Umar due to his difference with Ubayy who permitted prayer in a single garment in the sense that it is not offensive (makruh), while Ibn Mas`ud held that this was the case only at the time there was scarcity in clothing, whereupon `Umar went up to the pulpit and said: “What is right is what Ubayy said, and Ibn Mas`ud certainly did not fall short” (al-qawlu ma qala ubayy wa lam ya’il ibnu mas`ud).
Thus the decision of `Umar whereby he authorized praying in a single garment without blame is not a proof that “one was right and the other was wrong” as some superficial observers understand, rather it is a proof that `Umar exercised his own ijtihad and authority as the Greater Imam in settling the question. He ruled without dismissing any view. Furthermore, if Ibn Mas`ud held his position from the Prophet he cannot change it even after the ruling of the Greater Imam. This is true of every true mujtahid at any time: he is obligated to follow the result of his own ijtihad even if it should differ with that of every other mujtahid of the past and present, unless he becomes convinced that he was mistaken in his previous ijtihad.
According to all the scholars it is incumbent upon the leader of Muslims to be a mujtahid and it is his responsibility in such cases to settle the question for the sake of the people of his time, and that is the proper context of Imam Malik’s injuction: “Exercise ijtihad.” It is addressed to the mufti who must establish what is correct in clearcut fashion, not to the muqallid or follower who is only interested in “a way to follow” (= madhhab) without having to verify its proofs and inferences. The muqallid is not free to follow other than what he accepts as correct, nor is the ijtihad of the unqualified ever considered valid for others. However, another mufti may reach another conclusion and be followed, and is not bound by that of the first, nor are those who take their fatwa from him, and no-one finds fault with the other, as al-Layth ibn Sa`d stated. Those who condemn taqlid unconditionally are innovating in religion. As Ibn Qayyim said, there is a kind of taqlid that is even obligatory:
There is an obligatory (wajib) taqlid, a forbidden taqlid, and a permitted taqlid… The obligatory taqlid is the taqlid of those who know better than us, as when a person has not obtained knowledge of an evidence from the Qur’an or the Sunna concerning something. Such a taqlid has been reported from Imam al-Shafi`i in many places, where he would say: “I said this in taqlid of `Umar” or “I said that in taqlid of `Uthman” or “I said that in taqlid of `Ata’.” As al-Shafi`i said concerning the Companions — may Allah be well pleased with all of them: “Their opinion for us is better than our opinion to ourselves.”
A clear proof that the fatwa of the leader overrules but does not invalidate the opinion of the Companions even if it directly contradicts it, is the fact that when `Umar ibn al-Khattab proposed to have all the hadith collected and written down he consulted the Companions and they unanimously agreed to his proposal; later he disapproved of it and ordered that everyone who had written a collection burn it. Yet `Umar ibn `Abd al-`Aziz later ordered that hadith be collected and written.
Those who think they are mujtahid but in reality are unqualified, when faced by the followers of madhahib, camouflage their deviation under the claim: “We must follow Qur’an and Sunna, not madhahib.” When it is pointed out to them that to follow a madhhab is to follow Qur’an and Sunna through true ijtihad, they become upset: “How can the four madhhabs differ and be right at the same time? I have heard that only one may be right, and the others wrong.” The answer is that one certainly follows only the ruling that he believes is right, but he cannot fanatically invalidate the following of other rulings by other madhahib, because they also are based on sound principles of ijtihad. At this they rebel and begin numbering the mistakes of the mujtahids: “Imam Shafi`i was right in this, but he was wrong in that; Imam Abu Hanifa was right in this, but he was wrong in that…” They do not even spare the Companions. But when they are rebuked for this blatant disrespect “They become arrogant in their sin” (2:206). And this is the legacy of the “Salafi” movement.