(1)
A'ishah (RAA) narrated that the Messenger of Allah (ﷺ) said:
"Do not speak badly of the dead, they have already seen the result of (the deeds) that they sent on before them." Related by Al·Bukhari.
Reference: Bulugh al-Maram 596
In-book reference: Book 3, Hadith 65
English translation: Book 3, Hadith 621