✅Answer: Please refer to the following narrations:

1 عَنْ عُمَرَ بْنِ يَزِيدَ عَنْ أَبِي عَبْدِ اللَّه أَنَّهُ قَالَ: إِذَا مَاتَ الْمُؤْمِنُ فَحَضَرَ جِنَازَتَهُ أَرْبَعُونَ رَجُلًا مِنَ الْمُؤْمِنِينَ فَقَالُوا اللَّهُمَّ إِنَّا لَا نَعْلَمُ مِنْهُ إِلَّا خَيْراً وَ أَنْتَ أَعْلَمُ بِهِ مِنَّا قَالَ اللَّهُ تَبَارَكَ وَ تَعَالَى قَدْ أَجَزْتُ شَهَادَاتِكُمْ وَ غَفَرْتُ لَهُ مَا عَلِمْتُ مِمَّا لَا تَعْلَمُونَ.

📚Al-Faqih vol. 1, p. 165

Imam al-Sadiq, peace be upon him, said: When a believer dies, forty men from the believers should be present at his funeral and say:

اللَّهُمَّ إِنَّا لَا نَعْلَمُ مِنْهُ إِلَّا خَيْراً وَ أَنْتَ أَعْلَمُ بِهِ مِنَّا

Meaning: O God, we know nothing but good from him, and You are more knowledgeable than us about him!

Allah, the Blessed and Exalted, says: I have accepted your testimony, and I have forgiven what I knew about him from things you did not know!

2 عَنْ سَعْدٍ الْإِسْکَافِ قَالَ لَا أَعْلَمُهُ إِلَّا قَالَ عَنْ أَبِی جَعْفَرٍ قَالَ: قَدْ کَانَ فِی بَنِی إِسْرَائِیلَ عَابِدٌ فَأُعْجِبَ لَهُ دَاوُدُ فَأَوْحَی اللَّهُ عَزَّ وَ جَلَّ إِلَیْهِ لَا یُعْجِبْکَ شَیْ ءٌ مِنْ أَمْرِهِ فَإِنَّهُ مُرَاءٍ قَالَ فَمَاتَ الرَّجُلُ فَأُتِیَ دَاوُدُ وَ قِیلَ لَهُ مَاتَ الرَّجُلُ فَقَالَ دَاوُدُ ادْفِنُوا صَاحِبَکُمْ قَالَ فَأَنْکَرَتْ بَنُو إِسْرَائِیلَ وَ قَالُوا کَیْفَ لَمْ یَحْضُرْهُ قَالَ فَلَمَّا غُسِّلَ قَامَ خَمْسُونَ رَجُلًا فَشَهِدُوا بِاللَّهِ مَا یَعْلَمُونَ مِنْهُ إِلَّا خَیْراً قَالَ فَلَمَّا صَلَّوْا عَلَیْهِ قَامَ خَمْسُونَ آخَرُونَ فَشَهِدُوا بِاللَّهِ مَا یَعْلَمُونَ إِلَّا خَیْراً فَلَمَّا دَفَنُوهُ قَامَ خَمْسُونَ فَشَهِدُوا بِاللَّهِ مَا یَعْلَمُونَ مِنْهُ إِلَّا خَیْراً فَأَوْحَی اللَّهُ عَزَّ وَ جَلَّ إِلَی دَاوُدَ مَا مَنَعَکَ أَنْ تَشْهَدَ فُلَاناً فَقَالَ دَاوُدُ یَا رَبِّ لِلَّذِی أَطْلَعْتَنِی عَلَیْهِ مِنْ أَمْرِهِ قَالَ فَأَوْحَی اللَّهُ عَزَّ وَ جَلَّ إِلَیْهِ أَنَّ ذَلِکَ کَذَلِکَ وَ لَکِنَّهُ قَدْ شَهِدَ قَوْمٌ مِنَ الْأَحْبَارِ وَ الرُّهْبَانِ مَا یَعْلَمُونَ مِنْهُ إِلَّا خَیْراً فَأَجَزْتُ شَهَادَتَهُمْ عَلَیْهِ وَ غَفَرْتُ لَهُ عِلْمِی فِیهِ

📚Al-Kafi vol. 7, p. 405

Imam al-Baqir, peace be upon him, said: There was a devout worshipper among the Children of Israel whom David, upon our Prophet and his family and upon him be peace, was amazed by! God revealed to him: Let nothing of the matter of this worshipper amaze you, for he is a hypocrite!

He said: That worshipper died, and they came to David, upon our Prophet and his family and upon him be peace, and said: That worshipper has died!

David, upon our Prophet and his family and upon him be peace, said: Bury your companion!

The Children of Israel disapproved of this (it was unfamiliar to them) and said: How is it that he did not attend his funeral?!

When he was washed, fifty people stood up and testified for God that they knew nothing but good from him!

When they prayed over him, fifty more people stood up and testified for God that they knew nothing but good from him!

When they buried him, fifty more people stood up and testified that they knew nothing but good from this worshipper!

God revealed to David, upon our Prophet and his family and upon him be peace: What prevented you from attending the funeral of so-and-so (meaning that same worshipper)? He said: O God, because of what You informed me of about his matter! (i.e., his hypocrisy)!

God said: The matter was as you were informed, but a group of scholars and monks testified that they knew nothing but good from him, and I accepted their testimony and forgave what I myself knew about him!

✅Indeed, a believer who has lived among people in a way that other believers can testify that they knew nothing but good from him, God accepts the testimony of these believers and forgives what the people were not aware of. It is clear that this does not apply to everyone and every formal testimony.

✅The following narration is also beautiful:

3 الْفَضْل بْنِ عَبْدِ الْمَلِک عَنْ أَبِی عَبْدِ اللَّهِ عَنْ آبَائِه علیهم السلام قَال قَال رَسُولُ اللَّه : أَوَّلُ عُنْوَان صَحِیفَةِ الْمُؤْمِنِ بَعْدَ مَوْتِهِ مَا یَقُولُ النَّاسُ فِیهِ إِنْ خَیْراً فَخَیْراً و إِنْ شَرّاً فَشَرّاً

📚Amali Shaykh Tusi vol. 1, p. 45

Imam al-Sadiq, peace be upon him, narrated from his ancestors that the Messenger of God, peace be upon him and his family, said: The beginning of the title of a believer's book of deeds after his death is what people say about him. If (what people say) is good, (the title of his book of deeds) is good, and if it is evil and bad, it is evil!