Anas bin Malik reported,
A funeral procession passed by, and the people spoke well of the deceased. The Prophet ﷺ said, "It has become certain."Then another funeral passed by, and the people spoke ill of the deceased. He said, "It has become certain."Umar bin Khattab asked, "What has become certain?"He replied, "This one whom you praised, Paradise has become certain for him, and this one whom you spoke ill of, the Fire has become certain for him. You are Allah's witnesses on earth."
Azami 3640
Sahihعن أنس بن مالك قال
مروا بجنازة فأثنوا عليها خيرا فقال النبي ﷺ: وجبت ثم مروا بأخرى فأثنوا عليها شرا فقال: وجبت فقال عمر بن الخطاب: ما وجبت؟ قال: هذا أثنيتم عليه خيرا فوجبت له الجنة، وهذا أثنيتم عليه شرا فوجبت له النار، أنتم شهداء الله في الأرض.
Bukhari narrated it in "Funerals" (1367) from Adam, from Shuba, who said, Abdul-Aziz bin Suhayb told us, "I heard Anas bin Malik," and then he related the hadith. Muslim narrated it in "Funerals" (949) through another route from Ibn Ulaya, who said, Abdul-Aziz bin Suhayb informed us, with his chain of transmission, and in it the phrase "it is warranted, it is warranted, it is warranted" is repeated three times, whereupon Umar bin Khattab said, "May my father and mother be sacrificed for you." It also contains the Prophet's ﷺ statement, "You are Allah's witnesses on earth," repeated three times. Hakim added (1/377), "Allah has angels who speak on the tongues of the sons of Adam about the good and evil that is in a person," narrating it through another route from Nadr bin Anas, from Anas, and he graded it sahih according to the standard of Muslim.As for what is narrated from him as a raised report, "There is no man who dies for whom two men from among his closest righteous acquaintances bear witness, saying, 'O Allah, we know nothing of him but good,' except that Allah 
says to His angels, 'I bear witness that I have forgiven My servant on the basis of their testimony, and I have overlooked for him what they do not know,'" this is daif. Ishaq bin Rahawayh narrated it in his Musnad (359), saying, Baqiya bin Walid informed us, Dahhak bin Hamza told me, from Salih Amlouki, from Anas bin Malik, and then he related it.Dahhak bin Hamza is Wasiti, originally from Syria, and he is daif. Ibn Main said of him, "He is not much," and in another report, "He is nothing." Nasai said, "He is not reliable." Others among the scholars also criticized him. Ibn Adi said, "He has hasan, unusual hadiths." In Taqrib it says, "Daif."Baqiya bin Walid was a mudallis who practiced tadlis al-taswiya, meaning he did not explicitly state the manner of transmission at every level, as some scholars require for the acceptance of his hadith, out of concern for tadlis al-taswiya, though the majority accept his transmission regarding his own teachers.