Allah likes sneezing but dislikes yawning. So when one of you yawns, he should restrain it as much as possible, and should not say Ha, Ha, for that is from the devil who laughs at him. (Using translation from Abū Dāʾūd 5028)
أَنَّ رَسُولَ اللهِ ﷺ قَالَ إِنَّ اللهَ يُحِبُّ الْعُطَاسَ وَيَكْرَهُ التَّثَاؤُبَ فَإِذَا تَثَاءَبَ أَحَدُكُمْ فَقَالَ هَاهْ فَإِنَّ ذَلِكَ شَيْطَانٌ يَضْحَكُ مِنْ جَوْفِهِ