The Angel Gabriel is considered the most important of all the angels in Islam. In the Quran, the angel is called Jibreel or the Holy Spirit.
The Angel Jibreel’s main responsibility is to communicate the Words of Allah to His prophets. It is Jibreel who revealed the Quran to the Prophet Muhammad.
Examples From the Quran
The Angel Jibreel is mentioned by name in only a couple of verses of the Quran:
Say: Whoever is an enemy to Jibreel — for he brings down the revelation to your heart by Allah’s will, a confirmation of what went before, and guidance and glad tidings for those who believe — whoever is an enemy to Allah and His angels and apostles, to Jibreel and Mikail (Michael) — oh, Allah is an enemy to those who reject Faith. (2:97-98)
If you two turn in repentance to Him, your hearts are indeed so inclined. But if you back up each other against him, truly Allah is his Protector, and Jibreel, and every righteous one among those who believe, and furthermore, the angels will back him up. (66:4)
In another few verses, mention is made of the Holy Spirit (Ruh), which all Muslim scholars agree refers to the Angel Jibreel.
And truly this is a revelation from the Lord of the Worlds, which the trustworthy spirit (Jibreel) has brought down to your heart, in order that you may be from the warners, in plain Arabic language. (Quran 26:192-195)
Say, the Holy Spirit (Jibreel) has brought the revelation from your Lord in Truth, in order to strengthen those who believe, and as a Guide and Glad Tidings to Muslims. (16:102)
Other details about the nature and role of the Angel Gabriel come to us through Prophetic traditions (Hadith).
Jibreel would appear to the Prophet Muhammad at appointed times, to reveal verses of the Quran and ask him to repeat them. The Prophet would then listen, repeat, and memorize the words of Allah. The Angel Gabriel would often take on the shape or form of a man when appearing to the prophets.
At other times, he would share revelation by voice only.
Umar related that a man once came to a gathering of the Prophet and his companions — nobody knew who he was. He was extremely white with white clothing, and jet black hair. He proceeded to sit very close to the Prophet and questioned him in detail about Islam.
When the Prophet replied, the strange man told the Prophet that he had answered correctly. It was only after he left that the Prophet told his companions that this was the Angel Gabriel who had come to question and teach them about their faith. So there were others who were able to see Jibreel when he was in human form.
The Prophet Muhammad, however, was the only one who saw Jibreel in his natural form. He described Jibreel as having six hundred wings, that cover the sky from the earth to the horizon. One of the times he was able to see Jibreel in his natural form was during the Isra’ and Mi’raj.
It is also said that the Angel Jibreel carried out the destruction of the city of Prophet Lot, by using just the tip of one wing to turn the city upside-down.
Jibreel is most known for his important role of inspiring and communicating Allah’s revelation through the prophets (peace be upon them all).
Source: About Islam