To one who does you a favour1 du'a

May Allah reward you with good.

Reference:At-Tirmidhi (no. 2035). See also Al-Albani, Sahih At-Tirmidhi 2/200 and Sahihul-Jami' (no. 6244).Hisnul Muslim 198

جَزاكَ اللهُ خَـيْراً

Transliteration

Jazākallāhu khayra.

Translation

May Allah reward you with good.