The most beloved action to Messenger of Allah ﷺ was that whose doer did it continuously and regularly.  

أَنَّهَا قَالَتْ كَانَ أَحَبُّ الْعَمَلِ إِلَى رَسُولِ اللَّهِ ﷺ الَّذِي يَدُومُ عَلَيْهِ صَاحِبُهُ  

Yahya related to me from Malik from Hisham ibn Urwa from his father that A'isha, the wife of the Prophet ﷺ said, "The actions which the Messenger of Allah ﷺ loved most were those which were done most constantly."  

عَنْ عَائِشَةَ زَوْجِ النَّبِيِّ ﷺ أَنَّهَا قَالَتْ كَانَ أَحَبُّ الْعَمَلِ إِلَى رَسُولِ اللَّهِ ﷺ الَّذِي يَدُومُ عَلَيْهِ صَاحِبُهُ  

[Machine] The Messenger of Allah ﷺ loved the act of charity, as long as it was available to him, even if it was little.  

كَانَ أَحَبُّ الْعَمَلِ إِلَى رَسُولِ اللهِ ﷺ مَا دَامَ عَلَيْهِ وَإِنْ قَلَّ  

The most beloved action to Messenger of Allah ﷺ was that whose doer did it continuously and regularly. (Using translation from Bukhārī 6462)  

أَنَّهَا قَالَتْ «كَانَ أَحَبُّ الْأَعْمَالِ إِلَى رَسُولِ اللَّهِ ﷺ الَّذِي يَدُومُ عَلَيْهِ صَاحِبُهُ»  

[Machine] "The most beloved deeds to the Prophet Muhammad ﷺ were those done consistently, even if they were few."  

«كَانَ أَحَبُّ الْأَعْمَالِ إِلَى رَسُولِ اللهِ ﷺ مَا دِيمَ عَلَيْهِ وَإِنْ قَلَّ»  

"أحب العَمَل إلى الله: ما داوم عليه صاحِبُه، وإن قلّ".