كتاب الإيمان
1
The Book of Faith
(36)
Chapter: Clarifying that faith in Allah most high is the best of deeds
(36)
باب بَيَانِ كَوْنِ الإِيمَانِ بِاللَّهِ تَعَالَى أَفْضَلَ الأَعْمَالِ ‏‏

It is narrated on the authority of 'Abdullah b. Mas'ud that he observed. I asked the Messenger of Allah (ﷺ) which deed was the best. He (the Holy Prophet) replied:

Prayer at its appointed hour. I (again) said: Then what? He (the Holy Prophet) replied: Kindness to the parents. I (again) said: Then what? He replied: Earnest endeavour (Jihad) in the cause of Allah. And I would have not ceased asking more questions but out of regard (for his feelings).
حَدَّثَنَا أَبُو بَكْرِ بْنُ أَبِي شَيْبَةَ، حَدَّثَنَا عَلِيُّ بْنُ مُسْهِرٍ، عَنِ الشَّيْبَانِيِّ، عَنِ الْوَلِيدِ بْنِ الْعَيْزَارِ، عَنْ سَعْدِ بْنِ إِيَاسٍ أَبِي عَمْرٍو الشَّيْبَانِيِّ، عَنْ عَبْدِ اللَّهِ بْنِ مَسْعُودٍ، قَالَ سَأَلْتُ رَسُولَ اللَّهِ صلى الله عليه وسلم أَىُّ الْعَمَلِ أَفْضَلُ قَالَ ‏"‏ الصَّلاَةُ لِوَقْتِهَا ‏"‏ ‏.‏ قَالَ قُلْتُ ثُمَّ أَىٌّ قَالَ ‏"‏ بِرُّ الْوَالِدَيْنِ ‏"‏ ‏.‏ قَالَ قُلْتُ ثُمَّ أَىٌّ قَالَ ‏"‏ الْجِهَادُ فِي سَبِيلِ اللَّهِ ‏"‏ ‏.‏ فَمَا تَرَكْتُ أَسْتَزِيدُهُ إِلاَّ إِرْعَاءً عَلَيْهِ ‏.‏
Reference : Sahih Muslim 85 a
In-book reference : Book 1, Hadith 158
USC-MSA web (English) reference : Book 1, Hadith 151
  (deprecated numbering scheme)