((إِذَا رَأَى أَحَدُكُم مِنْ أَخِيهِ، أَوْ مِنْ نَفْسِهِ، أَوْ مِنْ مَالِهِ مَا يُعْجِبُهُ [فَلْيَدْعُ لَهُ بِالْبَرَكَةِ] فَإِنَّ الْعَيْنَ حَقٌّ)).
If you see anything of your brother that pleases you, or of his person or of his property [then ask Allah to bless him in it] for the envious eye is real.
Ahmad 4/447, Ibn Majah, Malik. Al-Albani graded it authentic in Sahihul-Jami' As-Saghir 1/212. Also see Al-Arna'ut's checking of Ibn Al-Qayyim's Zadul-Ma'ad 4/170.