The most beloved deeds to the Messenger of Allah ﷺ were those his companion maintained consistently.
قال قرأت على عبد الرحمن بن مهدي: مالك عن هشام بن عروة عن أبيه
كان أحب العمل إلى رسول الله ﷺ الذي يدوم عليه صاحبه
Its isnad is sahih, previously mentioned at 24700.