Has Anyone Seen Angels?

Is it possible for people to see the angels? Did our Prophet Muhammad (pbuh) see Gabriel in his genuine appearance?

We are not able to see the angels in their genuine appearance

Since the angels are of luminous, abstract matters, they cannot be perceived by the sense organs; thus it is not possible for us to see them in their genuine appearance.

However, we can see them when they assume the forms that we can see

There are many people in the past who saw the angels.
Narrated Ibn Abbas:
“The Prophet said on the day (of the battle) of Badr, "This is Gabriel holding the head of his horse and equipped with arms for the battle.”” (Bukhari, al-Maghaazi, 5, 59, 330)

Abdullah bin Abbas saw Gabriel beside Our Prophet (pbuh)

Abdullah bin Abbas narrated:

“My father and I were beside Our Prophet. Someone was speaking to Our Prophet. Our Prophet seemed not to pay any attention to my father. After we left, my father said: “O my son! Haven’t you seen that as if your uncle’s son (Prophet Muhammad) turned away from me?”
I said: “O my father! There was a person beside Our Prophet. He was speaking with him something secret.”
Thereupon, we turned back to Our Prophet. My father said: “O the Messenger of Allah! Abdullah (my son) told me that there was a man speaking with you. I wonder whether there was or not.”
The Prophet asked me: “O Abdullah! Have you seen him?” I replied: “Yes, I did.” He said to my father: “He was Gabriel. Gabriel was the one who hindered me from speaking with you.” (Imam Ahmad, Tabarani)
We understand from this hadith that, Abbas (ra) didn’t see Gabriel, so he thought that Prophet Muhammad turned away from him and didn’t speak with him. However, his son Abdullah, who was a child those days, saw Gabriel and understood why the Beloved Prophet (pbuh) couldn’t speak with them.

Urva bin Ruwaym narrated:

“Irdad bin Sariye was one of the sahabas (companions) of the Messenger of Allah (pbuh) and was quite old. Since he wanted to die, he invoked Allah saying: “O my Allah! I’ve got older. My bones have got weaker. Take me to Your presence!”
Irbad said that: “ı was in a Damascus masjid. Suddenly, a very smart adolescent having a green cloth on appeared and told me: “Why are you making such a supplication?” I asked: “How shall I pray?” He replied: “O my Allah! Beautify my deeds, allow my death.”
I said to him: “May Allah bless you! Who are you?”
He replied: “I’m Ribal who relieves the sorrow in the hearts of believers.” (Hayat-us Sahabe)
Ribal is the angel who is in charge of relieving the sorrow in hearts.

Our Prophet Muhammad (pbuh) saw Gabriel in his genuine form

The Messenger of Allah (pbuh) saw Gabriel (as) twice in his real form that has six hundred wings. Once, he saw him in sidrat-ul muntaha; for the second time he saw him in a region called Jiyad (that is below Makkah) in a situation covering the whole horizon (all directions of heaven). (Tirmizi, Bukhari, Muslim)

Angels would like the see the people, however they are not able to become visible to people without the permission of Allah (swt)

Some scholars say that angels descend in order to observe the worship of mankind and their enthusiasm and effort they display in obedience to Allah (swt).
“The angels and the Spirit descend therein, by the permission of their Lord, with all decrees.” (Surat-u Qadr, 4)
However, the expression “by the permission of their Lord” in the surat-u Qadr indicates that they ask their Lord for permission to see the people which means that they love people and want to see them. Yet, they ask permission from their Lord to descend and see. (Razi)
“(The angels say :) "We descend not, but by command of thy Lord.” (Surat-u Maryam, 64)
Some unbelievers wanted to see the angels as well, however angels didn’t become visible to them since Allah did not allow
“And they say: O you to whom the Reminder has been revealed! You are most surely insane: Why do you not bring to us the angels if you are of the truthful ones? We do not send the angels but with truth, and then they would not be respited.” (Surat-u Hijr, 6- 8)
Since the infidels wouldn’t have changed their mind and believed in Allah even if the angels had been sent down, Allah did not let them see the angels.