Companions of the Prophet followed by tabi‘un
The Companions of the Prophet (Arabic: اَلصَّحَابَةُ; aṣ-ṣaḥāba meaning "the companions", from the verb صَحِبَ meaning "accompany", "keep company with", "associate with") were the disciples and followers of Muhammad who saw or met him during his lifetime, while being a Muslim and were physically in his presence. "Al-ṣaḥāba" is definite plural; the indefinite singular is masculine صَحَابِيٌّ (ṣaḥābiyy), feminine صَحَابِيَّةٌ (ṣaḥābiyyah).
Later Islamic scholars accepted their testimony of the words and deeds of Muhammad, the occasions on which the Quran was revealed and other various important matters of Islamic history and practice. The testimony of the companions, as it was passed down through trusted chains of narrators (asānīd), was the basis of the developing Islamic tradition. From the traditions (hadith) of the life of Muhammad and his companions are drawn the Muslim way of life (sunnah), the code of conduct (sharia) it requires, and the jurisprudence (fiqh) by which Muslim communities should be regulated.
The two largest Islamic denominations, the Sunni and Shia, take different approaches to weighing the value of the companions' testimonies, have different hadith collections and, as a result, have different views about the ṣaḥābah.The second generation of Muslims after the ṣaḥāba, born after the death of Muhammad, who knew at least one ṣaḥāba, are called Tābi'ūn (also "the successors"). The third generation of Muslims after the Tābi'ūn, who knew at least one Tābi, are called tābi' al-tābi'īn. The three generations make up the salaf of Islam.Hadith
Sunni views
According to the History of the Prophets and Kings, after the death of the Islamic prophet Muhammad, Abu Bakr, Umar and Abu Ubaydah ibn al-Jarrah and the Anṣār of Medina held consultations and selected Abu Bakr as the first caliph. Then Abd al-Rahman ibn Awf and Uthman, companion and son-in-law of Muhammad and also essential chief of the Banu Umayyah, selected Umar as the second caliph after the death of Abu Bakr and the other Anṣār and Muhajirun accepted him.Sunni Muslim scholars classified companions into many categories, based on a number of criteria. The hadith quoted above shows ranks of ṣaḥābah, tābi'īn, and tābi' at-tābi'īn. Al-Suyuti recognized eleven levels of companionship.
The general involvement in military campaign with Muhammad by the ṣaḥāba was highlighted by the third generation scholar named Ibn al-Mubarak, who was once asked to choose between Mu'awiya ibn Abi Sufyan, who was a companion, and Umar ibn 'Abd al-'Aziz, who was famous for his piety. Ibn al-Mubarak simply responded: "...dust particles in Mu'awiyah's nose (while fighting in Hunayn under Muhammad) were better than six hundred Umar (ibn 'Abd al-'Aziz)..."