How does a Muslim ascend from the degree of Islam to faith (Iman) then to excellence (Ihsan)?

The ranks of religion are three: Islam, then Iman (faith), then Ihsan (excellence). Ihsan is the highest, Iman is the middle, and Islam is the lowest. Thus, the Muhsin (one who performs Ihsan) is a Mu'min (believer) and a Muslim (submitter), and the Mu'min is a Muslim.

Allah Almighty has divided people in the Quran into three categories: the one who wrongs himself, who is the Muslim who has not fulfilled the duty of Iman; the moderate (muqtasid), who is the Mu'min who has performed his obligations and avoided prohibitions; and the foremost in good deeds (sabiq bil-khayrat), who is the Muhsin who worships Allah as if he sees Him.

Whoever wrongs himself can ascend to the rank of Iman through sincere repentance, fulfilling obligations, and abandoning prohibitions. As for ascending to the rank of Ihsan and the station of those brought near (al-muqarrabun), this is achieved by performing supererogatory acts and abandoning unnecessary permissible things. The perfection of one's Ihsan and the elevation of one's rank depend on the extent of one's diligence in this regard.