It was narrated that Abu Hurairah said: “A funeral passed by the Prophet (ﷺ) and they praised (the deceased) and spoke well of him and mentioned his good characteristics. He said: ‘(Paradise is) guaranteed for him.’ Then another funeral passed by and they spoke badly of him and mentioned his bad characteristics, and he the Prophet (ﷺ) said: ‘(Hell is) guaranteed for him. You are the witnesses of Allah on earth.’”
Source: sunnah.com
Other translations
Arabic
حَدَّثَنَا أَبُو بَكْرِ بْنُ أَبِي شَيْبَةَ، حَدَّثَنَا عَلِيُّ بْنُ مُسْهِرٍ، عَنْ مُحَمَّدِ بْنِ عَمْرٍو، عَنْ أَبِي سَلَمَةَ، عَنْ أَبِي هُرَيْرَةَ، قَالَ مُرَّ عَلَى النَّبِيِّ ـ صلى الله عليه وسلم ـ بِجِنَازَةٍ - فَأُثْنِيَ عَلَيْهَا خَيْرًا فِي مَنَاقِبِ الْخَيْرِ فَقَالَ " وَجَبَتْ " . ثُمَّ مَرُّوا عَلَيْهِ بِأُخْرَى فَأُثْنِيَ عَلَيْهَا شَرًّا فِي مَنَاقِبِ الشَّرِّ فَقَالَ " وَجَبَتْ إِنَّكُمْ شُهَدَاءُ اللَّهِ فِي الأَرْضِ " .
sunnah.com