I asked the Prophet ﷺ, "Which deed is best?"He replied, "Faith in Allah and striving in His path." The hadith continues.
سألت النبي ﷺ أي العمل أفضل؟ قال: إيمان بالله وجهاد في سبيله الحديث.
Bukhari related it in the Book of Emancipation (2518), and Muslim in the Book of Faith (136:84), via Hisham bin Urwa, from his father, from Abu Marawih, from Abu Dharr, who narrated it.