‘Abdullāh ibn ‘Amr ibn al-‘Ās (may Allah be pleased with him) reported: The Messenger of Allah (may Allah’s peace and blessings be upon him) said: "Verily, faith wears out within one of you as a shirt becomes worn out; so, ask Allah to renew faith in your hearts."
The Prophet (may Allah's peace and blessings be upon him) says that faith wears out and weakens in the Muslim's heart as new clothing is worn out with long use. This stems from lethargy in worship or the commission of sins and indulgence in desires. So, the Prophet (may Allah's peace and blessings be upon him) instructed us to supplicate to Allah Almighty to renew our faith by performing our obligations and frequently remembering Him and asking Him for forgiveness.