Al-Adab Al-Mufrad, Hadith 950 ⓘ
Ibn Abbas said, "When someone yawns, he should place his hand over his mouth. Yawning comes from Shaytan."
حَدَّثَنَا عُثْمَانُ، قَالَ: حَدَّثَنَا جَرِيرٌ، عَنْ مَنْصُورٍ، عَنْ هِلاَلِ بْنِ يَسَافٍ، عَنْ عَطَاءٍ، عَنِ ابْنِ عَبَّاسٍ قَالَ: إِذَا تَثَاءَبَ فَلْيَضَعْ يَدَهُ عَلَى فِيهِ، فَإِنَّمَا هُوَ مِنَ الشَّيْطَانِ.
also referenced under: Book 40, Hadith 950 (In-Book) & Book 40, Hadith 950 (English)