Dua 15
When you thank someone back
وَإِيَّاكَ or وَإِيَّاكُمْ (Plural) وَأَنْتُمْ فَجَزَاكُمُ ٱللَّٰهُ خَيْرًا(Formal)
Wa iyyaak / Wa iyyaakum / Wa antum fajazakumullahu khayran
“And to you / And you too, may Allah reward you with goodness”
Tirmidhi 2035