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The Prophet ﷺ taught that saying Jazaka-llahu khayra to someone who has done you good is the most complete way to praise them.

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Thanking someone: Jazaka-llahu khayra

جَزَاكَ اللَّهُ خَيْراً

Jazaka-llahu khayra.

“May Allah reward you with good.”

Jami at-Tirmidhi 2035 (hasan)

The Prophet ﷺ said that whoever says this to someone who has done them a kindness has praised them in the fullest way.