Imān can grow with obedience to Allāh through good deeds and acts of worship, and it can weaken with sins and neglect. Each act of worship strengthens one’s faith, while disobedience causes it to diminish.
The Prophet Muhammad (peace be upon him) illustrated this concept when he said:
“Faith has seventy-odd branches, the highest of which is the statement ‘Lā ilāha illā Allāh’ (There is no deity worthy of worship except Allāh), and the lowest of which is removing something harmful from the road.”
— Sahih Muslim 35