How can a Muslim strengthen his faith?

It is established by the Qur’an, the Sunnah, and the consensus of the Companions and the Successors that faith increases with obedience and decreases with disobedience. Whoever wishes to strengthen their faith should comply with the commands of the Sharia and avoid its prohibitions, and increase in acts of obedience. As reported from Umar ibn Abd al-Aziz, "Indeed, faith has obligations, laws, limits, and sunnahs. Whoever fulfills them completely has completed faith." Thus, the strength of faith is linked to an increase in acts of obedience and certainty.