Sahih Muslim 783
Sahih Muslim · Book 6: The Book of Prayer - Travellers · The virtue of a deed that is done persistently, whether it be Qiyam al-Lail or anything else. The command to be moderate in worship, which means adopting what one can persist in. The command to the one who gets tired or weary when praying to stop until that feeling passes
'A'isha reported Allah's Messenger (ﷺ) as saying:
وَحَدَّثَنَا ابْنُ نُمَيْرٍ ، حَدَّثَنَا أَبِي ، حَدَّثَنَا سَعْدُ بْنُ سَعِيدٍ ، أَخْبَرَنِي الْقَاسِمُ بْنُ مُحَمَّدٍ ، عَنْ عَائِشَةَ ، قَالَتْ قَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم " أَحَبُّ الأَعْمَالِ إِلَى اللَّهِ تَعَالَى أَدْوَمُهَا وَإِنْ قَلَّ " . قَالَ وَكَانَتْ عَائِشَةُ إِذَا عَمِلَتِ الْعَمَلَ لَزِمَتْهُ .
The acts most pleasing to Allah are those which are done continuously, even if they are small. and when 'A'isha did any act she did it continuously.