What are the types of revelation?

All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His Slave and Messenger.

There were types of revelation sent down to the Prophet and they are as follows:

First, true visions. In this regard ‘Ubayd ibn ‘Umayr said, "Visions of Prophets are revelation," then he recited the verse in which Allah The Almighty Says (what means): {… indeed I have seen in a dream that I [must] sacrifice you …} [Quran 37:102]

Second, the angel used to cast revelation into the heart of the Prophet without seeing him, for the Prophet said: “The Holy Spirit (i.e. Jibreel) has cast in my heart (i.e. revealed to me) that no soul will die until it has completed its appointed term and received its provision in full, so fear Allah and graciously seek provision, and none of you should be tempted to seek provision by means of committing sin if it is slow in coming to him, for that which is with Allah can only be attained by obeying Him.”

Third, the angel (Jibreel) sometimes came to him in human form and talked to him and sometimes the Companions saw him in such a state.

Fourth, sometimes it is revealed to him like the ringing of a bell. This form of revelation is the hardest of all. After receiving the revelation in this form sweat used to drip from his forehead on a very cold day. Furthermore, his camel used to kneel down (due to the heaviness of the statement which was revealed to him). Additionally, once it was revealed to him while his thigh was resting on the thigh of Zayd ibn Thaabit and it became very heavy, to the extent that it would bruise Thaabit's thigh.

Fifth, what Allah, The Almighty, Revealed to him on Israa’ and Mi‘raaj (the Prophet’s night journey to Al-Aqsa mosque and then to the upper heavens) such as ordaining the five daily prayers and the like.

Ibn Al-Qayyim said: "The first revelation that his Lord Sent down to him (i.e. to the Prophet ) was to 'Read, in the Name of his Lord Who Has Created (all that exists).' This was the beginning of the Prophethood of the Messenger ; Allah, The Almighty, ordered him to worship Him in secret and not to proclaim the call of Islam. Then Allah Revealed to him {O you who covers himself [with a garment], Arise and warn.} [Quran 74:1-2]

By this, Allah commanded him to proclaim the call of Islam and ordered him to call his clan and closest relatives. Then he warned his people and those around them, then he warned all the Arabs, then he warned all of mankind. For over ten years, he kept calling to Islam without fighting or taking revenge, and Allah Ordered him to refrain from them and show patience. Later, Allah allowed him to migrate to Madeenah and fight. After that, Allah, The Almighty, ordered him to fight those who fought him and to refrain from those who did not fight him. Later, Allah, The Almighty, ordered him to fight the disbelievers until all and every kind of worship is for Allah, The Almighty, Alone."

Allaah Knows best.