(36) باب بَيَانِ كَوْنِ الإِيمَانِ بِاللَّهِ تَعَالَى أَفْضَلَ الأَعْمَالِ
It is reported on the authority of 'Abdullah that the Messenger of Allah observed:
The best of' the deeds or deed is the (observance of) prayer at its proper time and kindness to the parents.
Reference: Sahih Muslim 85 e
In-book reference: Book 1, Hadith 162
USC-MSA web (English) reference(deprecated numbering scheme): Book 1, Hadith 155