Sahih al Bukhari 6031
Good Manners and Form (Al-Adab)
حَدَّثَنَا أَصْبَغُ، قَالَ أَخْبَرَنِي ابْنُ وَهْبٍ، أَخْبَرَنَا أَبُو يَحْيَى، هُوَ فُلَيْحُ بْنُ سُلَيْمَانَ عَنْ هِلاَلِ بْنِ أُسَامَةَ، عَنْ أَنَسِ بْنِ مَالِكٍ ـ رضى الله عنه ـ قَالَ لَمْ يَكُنِ النَّبِيُّ صلى الله عليه وسلم سَبَّابًا وَلاَ فَحَّاشًا وَلاَ لَعَّانًا، كَانَ يَقُولُ لأَحَدِنَا عِنْدَ الْمَعْتَبَةِ " مَا لَهُ، تَرِبَ جَبِينُهُ ".
Narrated Anas bin Malik:The Prophet (ﷺ) was not one who would abuse (others) or say obscene words, or curse (others), and if he wanted to admonish anyone of us, he used to say: "What is wrong with him, his forehead be dusted
Text from the public-domain hadith-api dataset. Numbering follows that dataset and can differ by a few from some printed editions — check the wording, not only the number.