Asma' bint Yazid reported that the Prophet, may Allah bless him and grant him peace, said, "Shall I tell you who is the best of you?" "Yes,," they replied. He said, "Those who remind you of Allah when you see them." He went on to say, "Shall I tell you who is the worst of you?" "Yes," they replied. He said, "Those who go about slandering, causing mischief between friends in order to separate them, and desiring to lead the innocent into wrong action."
Source: sunnah.com
Other translations
Arabic
حَدَّثَنَا مُحَمَّدٍ، قَالَ: حَدَّثَنَا مُسَدَّدٌ، قَالَ: حَدَّثَنَا بِشْرُ بْنُ الْمُفَضَّلِ، قَالَ: حَدَّثَنَا عَبْدُ اللهِ بْنُ عُثْمَانَ بْنِ خُثَيْمٍ، عَنْ شَهْرِ بْنِ حَوْشَبٍ، عَنْ أَسْمَاءَ بِنْتِ يَزِيدَ قَالَتْ: قَالَ النَّبِيُّ صلى الله عليه وسلم: أَلاَ أُخْبِرُكُمْ بِخِيَارِكُمْ؟ قَالُوا: بَلَى، قَالَ: الَّذِينَ إِذَا رُؤُوا ذُكِرَ اللَّهُ، أَفَلاَ أُخْبِرُكُمْ بِشِرَارِكُمْ؟ قَالُوا: بَلَى، قَالَ: الْمَشَّاؤُونَ بِالنَّمِيمَةِ، الْمُفْسِدُونَ بَيْنَ الأَحِبَّةِ، الْبَاغُونَ الْبُرَآءَ الْعَنَتَ.
sunnah.com