Is the Hadith that states, "The deceased is testified for by forty [people]," authentic, and does that contradict the possibility that the deceased might have been among those who practiced showing off (riyaa'), and thus people falsely testify to his goodness?

The hadith (definition) mentioned in the question with the wording: “When a servant dies and his neighbors praise him and bear witness to his goodness, Allah the Almighty says: ‘I have accepted your testimony concerning him, and I have forgiven him for what you do not know’,” is not found in the available sources. However, Al-Bukhari, Ahmad, and An-Nasa’i narrated a similar hadith from Umar ibn Al-Khattab, may Allah be pleased with him, that the Prophet, peace and blessings be upon him, said: “Any Muslim for whom four people bear witness to his goodness, Allah will admit him into Paradise.” We said: “And three?” He said: “And three.” We said: “And two?” He said: “And two.”

This hadith does not contradict the possibility that the deceased might have been a hypocrite, because the acceptable testimony is that of people of virtue and truth, which corresponds to reality. There are two scholarly opinions regarding the meaning of the hadith: 1. That praise for goodness, when offered by people of virtue, corresponds to reality; otherwise, it does not. 2. That the hadith is general in its meaning, and that the praise of people of virtue and truth for the deceased is an indication that Allah the Almighty willed forgiveness for him, even if his deeds did not correspond to their testimony. This latter opinion is the one preferred by An-Nawawi.