Mukhtaṣar Ṣaḥīḥ Muslim · Kitāb al-Īmān
Muslim, 1/30 (no. 9); al-Bukhārī, no. 50. Mukhtaṣar no. 2.
The Messenger of Allāh ﷺ was one day sitting out among the people when a man came to him and said: “O Messenger of Allāh, what is faith?” He said: “That you believe in Allāh, His angels, His Book, His meeting, and His Messengers, and that you believe in the final resurrection.” He said: “O Messenger of Allāh, what is Islām?” He said: “Islām is that you worship Allāh and associate nothing with Him, establish the obligatory prayer, render the prescribed zakāh, and fast Ramaḍān.” He said: “O Messenger of Allāh, what is iḥsān?” He said: “That you worship Allāh as though you see Him; for if you do not see Him, He surely sees you.” He said: “O Messenger of Allāh, when is the Hour?” He said: “The one questioned of it knows no more than the questioner; but I shall tell you of its signs: when the slave-woman gives birth to her master, that is one of its signs; when the barefoot and naked become the heads of the people, that is one of its signs; and when the herdsmen of sheep vie with one another in raising tall buildings, that is one of its signs — among five that none knows but Allāh.” Then the man turned away, and he said: “Bring the man back to me.” They went to bring him back but saw nothing, and he said: “That was Jibrīl; he came to teach the people their religion.”
Summarised from al-Baḥr al-Muḥīṭ al-Thajjāj, 1/107–125
1. The three grades of the religion. Islām, Īmān, and Iḥsān gather the whole of the dīn; the Prophet ﷺ named the questioner's coming as teaching “the people their religion.”
2. When Islām and Īmān meet, they part. Named together, islām is set for the outward deeds and īmān for the inward beliefs; named singly, each includes the other.
3. Deeds enter the name of faith. Islām is defined here by acts — worshipping Allāh alone, the prayer, the zakāh, the fast — a proof against those who empty faith of works.
4. The Last Day is a pillar of faith. His placing of belief in “the meeting” and “the final resurrection” within īmān sets the Hereafter among the pillars, alongside Allāh, His angels, His Book, and His Messengers.
5. Iḥsān is the summit. “That you worship Allāh as though you see Him” is the station of murāqabah — worship performed by one certain his Lord beholds him; it is the highest of the degrees of faith.
6. The Hour is known to Allāh alone. Its hour is among the five keys of the unseen that none knows but Allāh; the Prophet ﷺ was no more knowing of it than the questioner, and turned him instead to its signs.
7. Teaching by question and answer. Jibrīl came in the form of a man and questioned the Prophet ﷺ before the people, that they might learn — a proof of the excellence of asking, and of teaching through it.