Definitions of companion
Most Muslims regard anyone who knew or saw God's last prophet Muhammed, believed in his teachings, and died as a Muslim to be a companion or Ṣahābi. Lists of prominent companions usually run to fifty or sixty names, being the people most closely associated with Muhammad. However, there were clearly many others who had some contact with prophet Muhammad. Many of them were identified by later scholars, and their names and biographies were recorded in religious reference texts such as prophet Muhammad ibn Sa'd's early Kitāb at-Tabāqat al-Kabīr.
It was important to identify the companions because later scholars accepted their testimony (the hadith, or traditions) as to the words and deeds of prophet Muhammad, the occasions on which the Qur'an was revealed, and various important matters of Islamic history and practice (sunnah). The testimony of the companions, as it was passed down through chains of trusted narrators (isnads), was the basis of the developing Islamic tradition.
Because the hadith were not written down until many years after the death of Muhammad, the isnads, or chains of transmission, always have several links. The first link is preferably a companion, who had direct contact with Muhammad. The companion then related the tradition to a taba'een, the companion of the companion. Taba'een had no direct contact with Muhammad, but did have direct contact with the Ṣahāba. The tradition then would have been passed from the taba'een to the taba taba'een, the third link.
The second and third links in the chain of transmission were also of great interest to Muslim scholars, who treated of them in biographical dictionaries and evaluated them for bias and reliability. Again, Shi'a and Sunni apply different metrics.
Numbers of companions
Some Muslims assert that there were more than one hundred thousand companions. They do so in relation to the hadith known as Ghadir Khumm, regarding a last sermon Muhammad delivered after making his last pilgrimage, or Hajj, to Mecca. Shi'a Muslims believe that there were about 124,000 witnesses to this sermon , which would emphasize the gravity and official nature of this alleged speech appointing Ali ibn Abi Talib as Muhammad's successor. Similar hadiths are found in Sunni sources but are not interpreted in the same way as the Shi'a interpret it. Sunni sources attach significance to the event in saying that the sermon was to dispel a growing hatred of Ali amongst the Muslims which Muhammad sought to curb.
Views of the companions
Soon after prophet Muhammad's death the Muslim community, the ummah, was riven by conflicts over leadership (worldly). Companions took sides in the conflicts – or were forced to take sides – and later scholars considered their allegiances in weighing their testimony. The two largest Muslim denominations, the Shia and Sunni take very different approaches in weighing the value of the companions' testimony.
"May God be pleased with him" (Arabic: Radhi-Allah-hu 'anhu رضي الله عنه) is usually mentioned after the names of the Sahaba.
According to Sunni scholars, people of the past should be considered companions if they had any kind of contact with prophet Muhammad. If they saw him, heard him, or were in his presence even briefly, they are companions. Blind people are considered companions even if they could not see Muhammad. Even unlearned and unobservant Muslims are considered companions. However, anyone who died after rejecting Islam and becoming an apostate is not considered a companion.
Sunni Muslim scholars classified companions into many categories, based on a number of criteria. Suyuti recognized eleven levels of companionship. However, all companions are considered just (udul); that is, Sunni scholars do not believe that companions would lie or fabricate hadith.
Shi'a Muslims do not accept all companions as just. The Shi'a believe that after the death of Muhammad, some Muslims turned aside from true Islam and followed leaders like the first caliphs, Abu Bakr and Umar. Only a few of the early Muslims held fast to Ali ibn Abi Talib, whom Shi'a Muslims regard as the rightful successor to Muhammad. (See Succession to prophet Muhammad) Shi'a scholars therefore deprecate hadith believed to have been transmitted through unjust companions, and place much more reliance on hadith believed to have been related by companions who supported Ali.
Qur'an alone views
Qur'an aloners view that the view pertaining that "ALL of them [were] good and righteous people" is the creation of "corrupted scholars and their blind followers disregarded [of] what God said in the Quran" .
- List of Sahaba
- Brotherhood among the Sahaba
- Non-Muslim interactants with Muslims during Muhammad's era.
- Timing of Sahaba becoming muslims
- Taba Tabe'een
Related to hadith:
Related to Muhammad's family:
- Munzir ibn Sawa Al Tamimi — became Muslim, but not a ṣaḥābi.
- ↑ To be with the truthful by Muhammad al-Tijani on Al-Islam.org 
- ↑ http://www.submission.org/muhammed/sahaba.html
- ↑ A Restatement of the History of Islam and Muslims on Al-Islam.org 
- Ibn Sa'd, Muhammad -- The book of The Major Classes, only partially translated into English; see Men of Medina and Women of Medina published by Ta-Ha Publishers, and first two volumes as published by Kitab Bhavan, New Delhi
- Wilferd Madelung -- The Succession to Muhammad, Cambridge University Press, 1997
- Maxime Rodinson -- Muhammad, 1961, as translated into English and published in 1980 by Pantheon Books
- William Montgomery Watt -- Muhammad at Medina, Oxford University Press 1956
- Companions of the Prophet - Great Compilation
- Companions of the Prophet - Excellent Compilation
- Men around the Messenger - Khalid Muhammad Khalid - download the pdf
- Islamic Glossary includes the names of some Sahaba.
- The Companions of the Prophet: Definition, Status, and Ranking
- Sahaba - Companions of the Prophet gives some detailed information about some Sahaba.
- ummah gives support to the idea that Imam Abu Hanifa was a taba'een
- Companions of the Prophet - the Sahabah provides extensive information about the lives of some Sahaba.
- Why are Sahaba the most successful An online video lecture by Shaykh Sayyed Muhammad bin Yahya Al-Husayni Al-Ninowy
- The Superior Qualities of Sahaba An online video lecture by Shaykh Sayyed Muhammad bin Yahya Al-Husayni Al-Ninowy
- The High Honor of Sahaba An online video lecture by Shaykh Sayyed Muhammad bin Yahya Al-Husayni Al-Ninowy
- al-Islam gives very short descriptions (both in English and Arabic) of some notable Sahaba.