The yawning as from the devil. So when one of you yawns he should try to restrain it as far as it lies in his power. (Using translation from Muslim 2994)
أَنَّ رَسُولَ اللهِ ﷺ قَالَ التَّثَاؤُبُ مِنَ الشَّيْطَانِ فَإِذَا تَثَاوَبَ أَحَدُكُمْ فَلْيَكْظِمْ مَا اسْتَطَاعَ