What to say when you fear you may afflict something with the evil eye

 244. 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.

Reference: 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.