A man would come to the Prophet ﷺ and embrace Islam only for some worldly gain he was given, yet by evening Islam would have become more beloved and precious to him than the world and everything in it.
حدثنا ابن أبي عدي عن حميد
كان الرجل يأتي النبي ﷺ فيسلم لشيء يعطاه من الدنيا فلا يمسي حتى يكون الإسلام أحب إليه وأعز عليه من الدنيا وما فيها
Its isnad is sahih, Muslim narrated it 4/1805 no. 2311 in the Virtues chapter, "The Messenger of Allah ﷺ was never asked for anything and said no."