Al-Adab Al-Mufrad, Hadith 942 ⓘ
Abu Hurayra reported that the Prophet, may Allah bless him and grant him peace, said, "When one of you yawns, he should repress it as much as possible."
حَدَّثَنَا عَبْدُ اللهِ بْنُ يُوسُفَ، قَالَ: أَخْبَرَنَا مَالِكٌ، عَنِ الْعَلاَءِ بْنِ عَبْدِ الرَّحْمَنِ، عَنْ أَبِيهِ، عَنْ أَبِي هُرَيْرَةَ، عَنِ النَّبِيِّ صلى الله عليه وسلم قَالَ: إِذَا تَثَاءَبَ أَحَدُكُمْ فَلْيَكْظِمْ مَا اسْتَطَاعَ.
also referenced under: Book 40, Hadith 942 (In-Book) & Book 40, Hadith 942 (English)