Among the most beloved deeds to Allah is gladdening a Muslim's heart. The Prophet ﷺ said: “The most beloved of people to Allah are those most beneficial to people; and the most beloved deed to Allah is a joy you bring to a Muslim…” (al-Ṭabarānī — ḥasan).
العربية: عن ابن عمر رضي الله عنهما أنّ النبيّ ﷺ قال: «أحبُّ الناس إلى الله أنفعهم للناس، وأحبُّ الأعمال إلى الله سرورٌ تُدخِله على مسلم». (الطبراني).
Brighten someone's day — a kind word, a gift, help with a debt, a visit — you please Allah by it.