Reports will never be accepted as true until [they are] verified by the eyes

لَنْ يَصْدُقَ الْخَبَرُ حَتَّى يَتَحَقَّقَ الْعِيَانُ

Source : Ghurar Al-Hikam Wa Durar Al-Kalim, Exalted Aphorisms And Pearls Of Speech

Seeing something [yourself] is not the same as being informed about it

لَيْسَ الْعِيَانُ كَالْخَبَرِ

Source : Ghurar Al-Hikam Wa Durar Al-Kalim, Exalted Aphorisms And Pearls Of Speech

Do not relate that which you have no knowledge about

لَا تُخْبِرْ بِمَا لَمْ تُحِطْ بِهِ عِلْماً

Source : Ghurar Al-Hikam Wa Durar Al-Kalim, Exalted Aphorisms And Pearls Of Speech

Do not relate to the people all that you hear, for this suffices as silliness (or foolishness)

لَا تُحَدِّثِ النَّاسَ بِكُلِّ مَا تَسْمَعُ فَكَفَى بِذَلِكَ خُرْقاً [حُمْقاً]

Source : Ghurar Al-Hikam Wa Durar Al-Kalim, Exalted Aphorisms And Pearls Of Speech

Do not say that which you do not know, thereby making others suspicious of your statements about what you do know

لَا تَقُلْ مَا لَا تَعْلَمُ فَتُتَّهَمَ بِإِخْبَارِكَ بِمَا تَعْلَمُ

Source : Ghurar Al-Hikam Wa Durar Al-Kalim, Exalted Aphorisms And Pearls Of Speech

Never transmit information except from a reliable person otherwise you will become a liar, and if you transmit from other than him then surely telling lies is [a cause of] disgrace and dishonour

لَا تُخْبِرَنَّ إِلَّا عَنْ ثِقَةٍ فَتَكُونَ كَذَّاباً وَإِنْ أَخْبَرْتَ عَنْ غَيْرِهِ فَإِنَّ الْكَذِبَ مَهَانَةٌ وَذُلٌّ

Source : Ghurar Al-Hikam Wa Durar Al-Kalim, Exalted Aphorisms And Pearls Of Speech

There is no good in that which is viewed except when accompanied with a good source of information [or good elocution]

لَا خَيْرَ فِي الْمَنْظَرِ إِلَّا مَعَ حُسْنِ الْمَخْبَرِ

Source : Ghurar Al-Hikam Wa Durar Al-Kalim, Exalted Aphorisms And Pearls Of Speech