Sahih al-Bukhari 3537
Book 61: Virtues and Merits of the Prophet (pbuh) and his Companions · Narrated by Anas
Arabic
حَدَّثَنَا حَفْصُ بْنُ عُمَرَ، حَدَّثَنَا شُعْبَةُ، عَنْ حُمَيْدٍ، عَنْ أَنَسٍ ـ رضى الله عنه ـ قَالَ كَانَ النَّبِيُّ صلى الله عليه وسلم فِي السُّوقِ فَقَالَ رَجُلٌ يَا أَبَا الْقَاسِمِ. فَالْتَفَتَ النَّبِيُّ صلى الله عليه وسلم فَقَالَ " سَمُّوا بِاسْمِي، وَلاَ تَكْتَنُوا بِكُنْيَتِي ".
English translation
Narrated Anas:While the Prophet (ﷺ) was in the market, a man called (somebody), "O Abu-l-Qasim!' The Prophet (ﷺ) turned to him and said "Name yourselves after me but do not call yourselves by my Kuniya
Reference: Sahih al-Bukhari 3537, Book of Virtues and Merits of the Prophet (pbuh) and his Companions. English translation by Dr. Muhammad Muhsin Khan.