The term aṣ-ṣaḥābah (Arabic: الصحابة meaning "the companions", from the verb صَحِبَ meaning "accompany", "keep company with", "associate with") refers to the companions, disciples, scribes and family of the Islamic prophet Muhammad. This form is definite plural; the indefinite singular is masculine sahabi (ṣaḥābī), feminine sahabia (ṣaḥābīyah).
Later scholars accepted their testimony of the words and deeds of Muhammad, the occasions on which the Quran was revealed and various important matters of Islamic history and practice. The testimony of the companions, as it was passed down through trusted chains of narrators (isnads), 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 in weighing the value of the companions' testimony, have different hadith collections and, as a result, have different views about the Sahabah.
The most widespread definition of a companion is someone who met Muhammad, believed in him and died as a Muslim. The Sunni scholar Al-Hâfidh Ibn Hajar (d.852H) – rahimahullâh – said: “The most correct of what I have come across is that a Sahâbî (Companion) is one who met the Prophet sallallâhu ’alayhi wa sallam whilst believing in him, and died as a Muslim. So, that includes the one who remained with him for a long or a short time, and those who narrated from him and those who did not, and those who saw him but did not sit with him and those who could not see him due to blindness.” [Source: Al-Isâbah (1/4-5) of al-Hâfidh lbn Hajar]