From Sahih Bukhari (Hadith 1367):
Narrated Anas bin Malik:A funeral procession passed and the people praised the deceased. The Prophet (ﷺ) said, "It has been affirmed to him." Then another funeral procession passed and the people spoke badly of the deceased. The Prophet (ﷺ) said, "It has been affirmed to him". `Umar bin Al-Khattab asked (Allah's Messenger (ﷺ) ), "What has been affirmed?" He replied, "You praised this, so Paradise has been affirmed to him; and you spoke badly of this, so Hell has been affirmed to him. You people are Allah's witnesses on earth
Reference: Bukhari 1367