Sahih al-Bukhari & Sahih Muslim

مَنْ كَانَ يُؤْمِنُ بِاللَّهِ وَالْيَوْمِ الآخِرِ فَلْيَقُلْ خَيْرًا أَوْ لِيَصْمُتْ

“Whoever believes in Allah and the Last Day, let him speak good or remain silent.”

— Sahih al-Bukhari & Sahih Muslim, Bukhari 6018, Muslim 47