Ihsaan
The spiritual excellence of worshipping God as though one sees Him, the highest dimension of faith.
Literally: doing what is beautiful, perfection
The highest tier of religion in the famous Hadith of Gabriel: "to worship God as though you see Him, and if you see Him not, He nevertheless sees you." Ihsaan is the perfection of faith into living, beautiful God-consciousness. Iqbal's whole project of the realized self resonates with this ideal of doing all things in the felt presence of God.
Ihsaan in Iqbal’s couplets
Sifaal-e-Hind se meena o jaam paida kar
Safaal-e-Hind se mina-o-jaam paida kar
Iman
Faith; the heart's assent to and trust in God, His prophets, and the unseen.
Islam
Submission to the will of God; the faith revealed through Prophet Muhammad.
Taqwa
God-consciousness; the reverent awareness of God that guards the soul from wrongdoing.
Mushahada
Direct spiritual witnessing or contemplative vision of the Divine reality.