Abdullah bin Abbas reported,

He reported that Abu Sufyan informed him that Heraclius said to him, "I asked you whether his followers were increasing or decreasing, and you claimed they were increasing. Such is faith, until it is complete. And I asked you whether anyone abandons his religion out of displeasure with it after having entered it, and you claimed that no one does. Such is faith, when its delight mingles with the hearts, no one becomes displeased with it."

Azami 148

Sahih

عن ابن عباس

أخبر أن أبا سفيان أخبره أن هرقل قال له: سألتك: هل يزيدون أم ينقصون؟ فزعمت أنهم يزيدون، وكذلك الإيمان حتى يتم وسألتك: هل يرتد أحد سخطة لدينه بعد أن يدخل فيه؟ فزعمت أن لا، وكذلك الإيمان حين تخالط بشاشته القلوب لا يسخطه أحد.

الأعظمي 148صحيح
Contents
Reference
Commentary
Ayat
Collection
Jami al-Kamil
Book
Faith
Chapter
Qualities of faith
Section
One whose heart is touched by the sweetness of faith will never be displeased with it
Numbering
Jami al-Kamil 148 (2nd edition)
Azami 148