إِذِ اللَّهُ- عَزَّ وَجَلَّ- يَصْرِفُ وَجْهَهُ عَنْ وَجْهِ الْمُصَلِّي إِذَا الْتَفَتَ فِي صَلَاتِهِ.
Because when the person praying turns his attention here and there during his prayer, Allah Almighty also turns His blessed face away from the face of the one praying.