The evil eye is genuine.  

عَنْ رَسُولِ اللَّهِ ﷺ قَالَ الْعَيْنُ حَقٌّ  

The man casting evil would be commanded to perform ablution, and then the man affected was washed with it.  

كَانَ يُؤْمَرُ الْعَائِنُ فَيَتَوَضَّأُ ثُمَّ يَغْتَسِلُ مِنْهُ الْمَعِينُ