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).
Source: sunnah.com
Other translations
Arabic
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 .
sunnah.com