Sahih al-Bukhari 6462
Sahih al-Bukhari · Book 81: To make the Heart Tender (Ar-Riqaq) · The adoption of a middle course, and the regularity of deeds
Narrated `Aisha:
حَدَّثَنَا قُتَيْبَةُ ، عَنْ مَالِكٍ ، عَنْ هِشَامِ بْنِ عُرْوَةَ ، عَنْ أَبِيهِ ، عَنْ عَائِشَةَ ، أَنَّهَا قَالَتْ كَانَ أَحَبُّ الْعَمَلِ إِلَى رَسُولِ اللَّهِ صلى الله عليه وسلم الَّذِي يَدُومُ عَلَيْهِ صَاحِبُهُ.
The most beloved action to Allah's Messenger (ﷺ) was that whose doer did it continuously and regularly.