Abu Sa'id Al-Khudri (May Allah be pleased with him) reported:
The Messenger of Allah (ﷺ) said, "When one yawns, he should put his hand over his mouth, otherwise the devil will enter."[Muslim]. (FR)
App reference (FR): Book 6, Hadith 40 (FR)
Arabic/English book reference (FR): Book 6, Hadith 884 (FR)