Dua when loving someone for Allah’s sake
أَحَبَّكَ الَّذي أَحْبَبْتَني لَه
أَحَبَّكَ الَّذي أَحْبَبْتَني لَه
Ahabbaka allathee ahbabtanee lah
Translation
May He for whose sake you love me, love you.
When to recite
Said to someone when informing them that you love them for the sake of Allah.
Source / Reference
Abu Dawud 4/333