A brief text delving into the topic of companions of the Holy Prophet (saw) from a Shi'a and Sunni perscpective.

Were All Companions Just and Truthful?
“O Believers, if an unrighteous person comes to you with information, you should verify it or else you might inflict harm on a people in ignorance and then end up regretting what you have done” (Holy Qur'an: Chapter 49, Verse 6)
The Shi'ah are devoted to all those Companions of the Prophet Muhammad (s) who were loyal to his teachings in his life and remained so after his death. According to the Sunni view, even those who merely saw the Prophet (s) for a few seconds are called Companions and are considered immune from criticism. This idea is not supported by the Qur'an or historical facts, and has led too much of the difference between the two schools of thought.

A Companion Defined
Ibn Hajar al-'Asqalani, the famous Sunni scholar, defined a Companion of the Prophet (s) as a person who met the Prophet Muhammad (s), after having accepted Islam, and died while still being a Muslim.
He included in this definition the following:
• all those people who met the Prophet (s), irrespective of the fact whether it was for a long period or a very brief one,
• those who transmitted traditions from the Prophet (s) and those who did not,
• those who fought along with the Prophet (s) and those who did not,
• those who merely saw the Prophet (s) but did not sit in a gathering with him,
• as well as those who did not see him due to any excuse such as being blind.
[Ibn Hajar al-'Asqalani, al-‘Isabah fi Tamyiz al-Sahaba, (Beirut), vol. 1, p. 10]

Were All Companions Just and Truthful?
The Ahl al-Sunnah are unanimous on the issue that all the Companions were just and trustworthy and that they were the best of the ummah. Many Sunni scholars have stated this belief, including:
• Ibn Hajar al-'Asqalani, al-‘Isabah fi Tamyiz al-Sahaba, (Cairo), vol. 1, pp. 17-22
• Ibn Abi Hatim al-Razi, al-Jarh wa al-Ta'dil, (Hyderabad), vol. 1, pp. 7-9
• Ibn al-'Athir, Usd al-Ghaba fi Ma'rifat al-Sahaba, vol.1, pp. 2-3
This concept is difficult to accept in the light of indisputable evidence to the contrary. Consider the following example:
• "Az-Zubair told me that he quarrelled with an Ansari man who had participated in (the battle of) Badr in front of Allah's Apostle about a water stream which both of them used for irrigation. Allah's Apostle said to Az-Zubair, "O Zubair! Irrigate (your garden) first, and then let the water flow to your neighbor." The Ansari became angry and said, "O Allah's Apostle! Is it because he is your cousin?"
On that the complexion of Allah's Apostle changed (because of anger) and said (to Az-Zubair), "Irrigate (your garden) and then with-hold the water till it reaches the walls (surrounding the palms)." So, Allah's Apostle gave Az-Zubair his full right. Before that Allah's Apostle had given a generous judgment beneficial for Az-Zubair and the Ansari, but when the Ansari irritated Allah's Apostle he gave Az-Zubair his full right according to the evident law. Az-Zubair said, "By Allah ! I think the following Verse was revealed concerning that case: "But no by your Lord They can have No faith Until they make you judge In all disputes between them." (4.65)" [Sahih al-Bukhari (English translation), volume 3, book 49, number 871]
According to the Sunni doctrine this Companion of the Prophet (s) would be beyond reproach as an authority on sunnah and his actions would be a model to be followed. This is despite the fact that this Companion not only refused to accept the judgment of the Prophet (s) but caused him grief resulting in the revelation of the Qur'anic verse.
Unfortunately, Islamic history is replete with many examples of such people who, although they meet the Sunni criteria to be called Companions, behaved in an un-Islamic way. This behavior was exhibited during the Prophet's (s) life or afterwards or both!
Al-Walid bin 'Uqbah
Is he then who is a believer like he who is a transgressor (fasiq)? They are not equal. (Qur'an: Surah al-Sajdah, verse 18)
Leading Sunni commentators tell us that the context of the revelation of this verse was an incident whereby the word "believer" referred to Imam 'Ali b. Abi Talib and the "transgressor" (fasiq) refered to a Companion of the Prophet (s) called al-Walid bin 'Uqba bin Abi Mu'ayt.
• al-Qurtubi, Tafsir, (Cairo, 1947), vol. 14, p. 105
• al-Tabari, Tafsir Jami' al-Bayan, under commentary for this verse
• Al-Wahidi, Asbab al-Nuzul, (Dar al-Diyan li-Turath edition), p. 291
We have already seen the Qur'anic verse that forbids believers from blindly believing any news transmitted by a fasiq:
O ye who believe! if a wicked person (fasiq) comes to you with any news, ascertain the truth, lest ye harm people unwittingly, and afterwards become full of repentance for what ye have done. (Surah al-Hujurat, verse 6)
It is interesting to note that the exegesis of this verse indicates another incident where the same al-Walid lied about a matter that led to the revelation of this verse declaring him a transgressor (fasiq).
• Ibn Kathir, Tafsir Qur'an al-'Azim, (Beirut, 1987), vol. 4, p. 224
• al-Qurtubi, Tafsir, (Cairo, 1947), vol. 16, p. 311
• al-Suyuti and al-Mahalli, Tafsir al-Jalalayn, (Cairo, 1924), vol. 1, p. 185
• Abu Ameenah Bilal Philips, Tafseer Soorah al-Hujuraat, (Riyadh), pp. 62-63
As Abu Ameenah Bilal Philips says, “great caution must always be taken when dealing with information conveyed by people of doubtful character, those whose honesty has not yet been proven or by known sinners”. However, we find in the Sunni hadith collections traditions of the Prophet (s) on the authority of al-Walid! See, for example:
• Abu Dawud, Sunan, (1973), Kitab al-Tarajjul, bab fi'l-khuluq li'r-rijal, vol. 4, p. 404, hadith number 4181
• Ahmad bin Hanbal, al-Musnad, awwal musnad al-madaniyyin ajma'in, hadith 15784
Al-Walid's wickedness did not end during the Prophet's (s) time. He was appointed governor of al-Kufah by 'Uthman, the third caliph, where his wickedness continued. Once he led the morning prayers in a condition of intoxication and prayed four instead of two units. He was subsequently given the punishment on the orders of 'Uthman. This incident is mentioned in countless sources including some mentioned above, as well as:
• Sahih al-Bukhari (English translation), volume 5, book 57, number 45; volume 5, book 58, number 212
Al-Tabari, Ta'rikh, (English translation: History of al-Tabari, The Crisis of the Early Caliphate), volume XV, p.120
Sunni legal experts use precisely this precedent of the wicked (fasiq) Companion al-Walid to legalise praying behind a person who is an open sinner!!
• 'Ali al-Qari al-Harawi al-Hanafi, Sharh Fiqh al-Akbar, under chapter 'it is permissible to pray behind a good person or a wicked person', p. 90
• Ibn Taymiyyah, Majmu' Fatawa, (Riyadh, 1381), vol. 3, p. 281

But why not let bygones be bygones?
If we uncover the faults of Companions such as al-Walid, it is not because of any perverse desire to backbite. Rather, it is because Muslims need to be very careful of where they get their information from regarding the tenets of Islam and the sunnah of the Prophet (s). This can only be determined by paying careful attention to the lives of all the Companions of the Prophet (s), and letting their own deeds speak for their character and trustworthiness. After all, the Prophet (s) has already warned us
• "I shall arrive at the Pool before you, and he who passes by me will drink, and whoever drinks from it will never feel thirsty. There will come to me people that I know and they know me, but we shall be separated, then I shall say, 'My companions'. An answer shall come, 'You do not know what they did after you'. Then I shall say, 'Away with those who changed after me.'" [Sahih al-Bukhari (English translation), volume 8, book 76, number 585]
 

The Shi'i View on the Companions
The Shi'ah love the sincere Companions of the Prophet (s) who are praised in the Qur'an. This praise does not cover individuals such as al-Walid bin 'Uqbah who, despite meeting the Sunni criteria of Companionship, cannot be considered role models or reliable transmitters of the sunnah.
The Shi'ah therefore do not believe in the universal integrity of all Companions but examine the history of each Companion to discover his or her adherence to the Prophetic message. Of course there were many such Companions including but not restricted to 'Ammar, Miqdad, Abu Dharr, Salman, Jabir, and Ibn 'Abbas. We conclude with an extract from a supplication by the fourth Shi'ah Imam Zayn al-'Abidin (a) in praise of these noble Companions, may Allah be well pleased with them:
O God, and as for the Companions of Muhammad specifically, those who did well in companionship, who stood the good test in helping him, responded to him when he made them hear his messages' argument, separated from mates and children in manifesting his word, fought against fathers and sons in strengthening his prophecy, and through him gained victory; those who were wrapped in affection for him, hoping for a commerce that comes not to naught in love for him; those who were left by their clans when they clung to his handhold and denied by their kinsfolk when they rested in the shadow of his kinship; forget not, O God, what they abandoned for Thee and in Thee, and make them pleased with Thy good pleasure for the sake of the creatures they drove to Thee while they were with Thy Messenger, summoners to Thee for Thee.
[Imam Zayn al-'Abidin , Sahifa al-Kamilah, (English translation, London, 1988), p. 27]