Silsilat al-Ahadith al-Sahihah

It is narrated from Sayyiduna Rabi’ bin Mu’awwiz (may Allah be pleased with him) that the Noble Prophet (peace and blessings of Allah be upon him) said: "When people offer the funeral prayer for a deceased person and praise him, Allah Almighty says: I have enforced the testimony of My servants based on the good deeds which they know, and I have forgiven the bad deeds which they do not know."

Muhammad bin Ziyad Al-Hani says: When the people who possess the ruling of martyrdom were mentioned in the presence of Abu ‘Unbah Khawlani, those present mentioned people who died from abdominal illness, those who died from plague, and women who died during childbirth. But Abu ‘Unbah became angry and said: The noble Companions (may Allah be pleased with them) narrated to us from the Prophet (peace and blessings of Allah be upon him) that he said: “The trustworthy people among the creation of Allah are the witnesses of Allah on earth, whether they are martyrs or those who die a natural death.”

Abu Huraira (may Allah be pleased with him) narrates that people praised a funeral that passed by the Prophet (peace and blessings of Allah be upon him). The Prophet (peace and blessings of Allah be upon him) said: “(Paradise) has become obligatory.” After that, people spoke ill of another funeral that passed by, and upon hearing this, the Prophet (peace and blessings of Allah be upon him) said: “(Hell) has become obligatory.” And then he said: “You are witnesses over one another.”

Sayyiduna Yazid bin Shajarah (may Allah be pleased with him) says: The Messenger of Allah (peace and blessings be upon him) went out with a funeral. The people spoke good words about the deceased and praised him. At that moment, Jibreel (the trustworthy) came and said: "This man was not as the people are saying, but you are Allah’s witnesses on earth, so (in view of your testimony) Allah forgave even those sins of his which these people did not know about."