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.
Belief in the Angels is a part of belief in the Unseen and a Muslim must limit his knowledge to what was conveyed through revelation. Belief in the Angels is one of the main six pillars of faith, second to the belief in Allaah The Almighty. Allaah The Almighty Says (what means): {The Messenger has believed in what was revealed to him from his Lord, and [so have] the believers. All of them have believed in Allaah and His Angels.} [Quran 2:285] When the Prophet, sallallaahu ‘alayhi wa sallam, was asked about faith, he said: "To believe in Allaah, His Angels, His Books, His Messengers, the Last Day, and to believe in destiny, whether good or evil." [Muslim]
The Angels are the honorable slaves of Allaah The Almighty Who created them from light. They neither eat, nor drink, nor sleep. They glorify Allaah The Almighty night and day and do not slacken. They do not disobey the orders of Allaah The Almighty and they carry out what they are commanded to do. They cannot precede Him in word, and they act by His command. They cannot intercede except on behalf of one whom He approves, and they are apprehensive from fear of Him. They are assigned by Allaah The Almighty tasks in the heavens and on earth and every movement in this universe. Allaah The Almighty Says (what means):
• {And those who arrange [each] matter.} [Quran 79:5]
• {And those [angels] apportioning [each] matter.} [Quran 51:4]
Allaah The Almighty alone knows their number, as He Says (what means): {And none knows the soldiers of your Lord except Him.} [Quran 74:31]
To conclude, belief in the angels is one of the fundamentals of the Muslim's creed, and that they are honored slaves of Allaah The Almighty, who neither eat, drink, nor sleep.
Allaah Knows best.