Sunan Ibn Majah, Book 5, Hadith 1021 (In-Book) ⓘ
It was narrated from Abu Hurairah that the Messenger of Allah said: “When anyone of you yawns, let him put his hand over his mouth and not make a sound, because Satan laughs at him.”
حَدَّثَنَا مُحَمَّدُ بْنُ الصَّبَّاحِ، أَنْبَأَنَا حَفْصُ بْنُ غِيَاثٍ، عَنْ عَبْدِ اللَّهِ بْنِ سَعِيدٍ الْمَقْبُرِيِّ، عَنْ أَبِيهِ، عَنْ أَبِي هُرَيْرَةَ، أَنَّ رَسُولَ اللَّهِ ـ صلى الله عليه وسلم ـ قَالَ " إِذَا تَثَاءَبَ أَحَدُكُمْ فَلْيَضَعْ يَدَهُ عَلَى فِيهِ وَلاَ يَعْوِي فَإِنَّ الشَّيْطَانَ يَضْحَكُ مِنْهُ " .
also referenced under: Hadith 968 (Reference) & Volume 2, Book 5, Hadith 968 (DarusSalam)