I heard the Messenger of Allah ﷺ say: He who lets his garment trail during prayer out of pride, Allah, the Almighty, has nothing to do with pardoning him and protecting him from Hell.
سَمِعْتُ رَسُولَ اللَّهِ ﷺ يَقُولُ مَنْ أَسْبَلَ إِزَارَهُ فِي صَلاَتِهِ خُيَلاَءَ فَلَيْسَ مِنَ اللَّهِ فِي حِلٍّ وَلاَ حَرَامٍ