Recognition of the Companions - advice by Imam Sadiq (as)

Do not forsake certainty for doubt, and what is clear for what is hidden.
Do not pass judgement on what you cannot see because of something
you are told about it. Allah despises slander and bad opinion of your believing
brothers. What then does He think of boldness in attributing a
false statement, false belief or lie to the Companions of the Messenger of
Allah?
As He said,

When you welcomed it with your tongues, and spoke with your
mouths that which you had no knowledge of, and you deemed it an easy
matter while with Allah it was grievous. (24:15)


As long as you can find a way to speak well and act well of people
whether or not they are present. Do not do anything else. Allah said,

Speak to men good words. (2:83)

Know that Allah chose companions for His Prophet, honored them
with the noblest mark of honor and robed them in the robe of support,
victory and the correct keeping of his company in desirable and undesirable
situations. He made the tongue of His Prophet speak about their virtues,
excellent qualities and marks of honor; so believe in their love,
mention their excellence, and beware of the company of people of innovation,
for it will make disbelief and clear loss grow in the heart. If the excellence
of some of them is not clear to you, then leave them to the
Knower of the Unseen, and say, 'O Allah, I love anyone You and Your
Messenger love, and I hate anyone You and Your Messenger hate.' There
is no obligation beyond that.

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Reference: Book Lantern of Path, compiled by the teachings of Imam Sadiq (as), hadith on "recognition of a companion".