Abu Darda reported:

The Prophet, peace and blessings be upon him, said, “Shall I not tell you of the best of your deeds, which is the purest to your King, which raises you among your ranks, which is better for you than spending gold and money in charity, and which is better for you than meeting your enemy and striking the necks of each other?” They said, “Of course!” The Prophet (ﷺ) said, “It is the remembrance of Allah Almighty.”

Sunan al-Tirmidhī 3377
Sahih according to Al-Albani