I was riding on a mount behind the prophet (May peace be upon him). It stumbled. Thereupon I said: May the devil perish! He said: do not say; may the devil perish! For you say that, he will swell so much so that he will be like a house, and say: by my power. But say: in the name of Allah; for when you say that, he will diminish so much so that he will be like a fly.
كُنْتُ رَدِيفَ النَّبِيِّ ﷺ فَعَثَرَتْ دَابَّتُهُ فَقُلْتُ تَعِسَ الشَّيْطَانُ فَقَالَ لاَ تَقُلْ تَعِسَ الشَّيْطَانُ فَإِنَّكَ إِذَا قُلْتَ ذَلِكَ تَعَاظَمَ حَتَّى يَكُونَ مِثْلَ الْبَيْتِ وَيَقُولَ بِقُوَّتِي وَلَكِنْ قُلْ بِسْمِ اللَّهِ فَإِنَّكَ إِذَا قُلْتَ ذَلِكَ تَصَاغَرَ حَتَّى يَكُونَ مِثْلَ الذُّبَابِ