All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His Slave and Messenger.
In principle, teamwork is a form of cooperation, support and brotherhood on the straight path of Allaah The Almighty. It is not only permissible under Sharee‘ah but indeed recommended, based on evidence that proves the merit of the group. However, if this leads to partiality; enthusiasm for certain names or slogans, and rejection and denial of the truth when it comes from another group, then it is impermissible. As long as the group the person intends to join adopts the methodology of Ahl As-Sunnah wa'l-Jamaa‘ah in creed, thought, conduct and methodology, it is permissible to cooperate with them and support the truth they advocate.
However, it is important to know that truthful people are recognized by their adherence to the Book of Allaah and the Sunnah of the Prophet, sallallaahu ‘alayhi wa sallam . Also, the words of any person are subject to being accepted or rejected except the words of the Prophet, sallallaahu ‘alayhi wa sallam. Obeying others depends on how obedient they are to Allaah The Almighty and His Messenger, sallallaahu ‘alayhi wa sallam. Muslims should adapt themselves to accept the truth from anyone who upholds the truth regardless of his station in life or affiliation.
We advise anyone who cooperates with these groups to be clear and frank in his methodology and explain to his brothers that he follows the truth and that his work with a certain group does not mean that he disassociates or hates the others. Rather, every believer is supported and loved according to the extent of his obedience and religiousness, regardless of his sect or group.
Giving an oath of allegiance to a certain name, slogan or person is the practice of those who innovate in religion. Whoever claims that it is obligatory to give him or his group the oath of allegiance and quotes the Hadeeth of the oath of allegiance as evidence for his claim is an innovator in religion and is contradicting the methodology of Ahl As-Sunnah wa'l-Jamaa‘ah. The oath of allegiance which is mentioned in the Hadeeth is only given to the general commander of the believers who is accepted by all people.
It should be taken into consideration that though these groups intend to support the truth and call for adherence to Islamic teachings, they differ regarding the soundness and comprehensiveness of methodology regarding the different aspects of Islam. Islam is not represented by just one specific group. The most that could be said about these groups is that they are different ways of doing Da‘wah and understanding Islam under its domain.
The majority of Muslims, even though there exist among them scholars, callers to Allaah The Almighty and Mujaahids (holy warriors), do not belong to any of these groups. Therefore, we have to understand the reasons behind the formation of these groups, put them in their proper framework and not use varied means of Da‘wah that lead to ends that contradict the basic aim.
Nevertheless, we find that the Islamic groups undertaking the responsibility of Da‘wah and Islamic work are constantly growing. Therefore, we believe that the current groups are sufficient for the purpose at hand. The formation of new groups does not serve the call for unity of Muslims in their views and efforts.
Allaah Knows best.