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, say
“O Allah send blessings upon him. (This is) that which Allah has willed, there is no power except with Allah.”
اللّهُـمَّ بارِك عَلَـيه ما شاءَ الله، لا قُوَّةَ إلاّ بالله
Allahumma baarik ‘alayh. Ma shaa`allah laquwwata illa billah.
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