Al-Kāfi - Volume 2 > Balanced and Continuous Good Deeds
Hadith #2

2ـ عَلِيُّ بْنُ إِبْرَاهِيمَ عَنْ أَبِيهِ عَنْ حَمَّادِ بْنِ عِيسَى عَنْ حَرِيزٍ عَنْ زُرَارَةَ عَنْ أَبِي جَعْفَرٍ (عَلَيهِ السَّلام) قَالَ قَالَ أَحَبُّ الأعْمَالِ إِلَى الله عَزَّ وَجَلَّ مَا دَاوَمَ عَلَيْهِ الْعَبْدُ وَإِنْ قَلَ‏.

2. Ali ibn Ibrahim has narrated from his father from Hammad ibn ‘Isa from Hariz from Zurara from abu Ja’far (a.s.) who has said the following: “Abu Ja’far (a.s.) has said, ‘The most beloved deed in the sight of Allah, the Most Majestic, the Most Holy, is that which is continued even though it is very little.’”