Short answer
Mikail (Michael) is one of the greatest angels in Islam. The Quran names him beside Jibril (2:98), and the Prophet ﷺ named him in his night prayer. Many scholars say Allah has put him in charge of rain and the growth of plants, and so of the provision of creatures.
Belief in the angels is a pillar of iman, and that includes the angels that revelation names, such as Jibril and Mikail. Rejecting an angel the Quran names is rejecting the Quran itself. Details of his duties are believed only as far as the reports about them are sound.
The four schools agree on this.
Explanation
Mikail, also spelled Mika'il, Mikal or Mikael, is the angel known in English as Michael. The Quran names him once: "Whoever is an enemy to Allah and His angels and His messengers and Gabriel and Michael, then indeed, Allah is an enemy to the disbelievers" (2:98). Commentators report that some Jews of Madinah said they would follow the Prophet ﷺ if his angel were Mikail rather than Jibril. The verse answers that the angels are one camp: to be hostile to one is to be hostile to Allah.
The Prophet ﷺ began his night prayer with a dua that names him: "O Allah, Lord of Jibril, Mikail and Israfil, Creator of the heavens and the earth" (Sahih Muslim). In a long dream recorded in Sahih al-Bukhari, the two angels who guided him said, "I am Jibril and this is Mikail." At Uhud, Sa'd ibn Abi Waqqas saw two men in white he had never seen before or after, fighting fiercely on the right and left of the Messenger of Allah; a narrator explained that they were Jibril and Mikail (Sahih Muslim).
What does he do? Many commentators, going back to reports from Ibn Abbas, say Mikail is entrusted with rain and plants, and through them the provision of living things. This is widely taught, but it rests on reports from the early generations rather than a clear verse, so hold it as a well-known explanation. Detailed descriptions of his form are not authentic, so leave them.
Muslims honour Mikail but do not pray to him, ask him for rain, or picture him with a sword as Christian art does. Every dua goes to Allah alone. Read more in Angels in Islam and the four great angels.
The evidence
Quran, Surah Al-Baqara 2:98
مَن كَانَ عَدُوًّۭا لِّلَّهِ وَمَلَٰٓئِكَتِهِۦ وَرُسُلِهِۦ وَجِبْرِيلَ وَمِيكَىٰلَ فَإِنَّ ٱللَّهَ عَدُوٌّۭ لِّلْكَٰفِرِينَ ﴿٩٨﴾
Whoever is an enemy to Allah and His angels and His messengers and Gabriel and Michael - then indeed, Allah is an enemy to the disbelievers.
Names Mikail beside Jibril and warns against hostility to any angel.
Sahih Muslim 770
Sahih... اللهم رب جبرائيل وميكائيل وإسرافيل فاطر السموات والأرض ...
"O Allah, Lord of Jibril, Mikail and Israfil, Creator of the heavens and the earth."
The Prophet ﷺ named Mikail among the greatest angels in his night prayer.
Sahih al-Bukhari 1386
Sahih... وأنا جبريل وهذا ميكائيل فارفع رأسك ...
"I am Jibril and this is Mikail, so raise your head."
The angels introduce themselves to the Prophet ﷺ by name in his dream.
Where the ruling is recorded
- al-Fiqh al-Akbar (Imam Abu Hanifa), Opening section on the articles of belief. Lists belief in the angels among the foundations of iman.
- Tafsir Ibn Kathir, Commentary on Surah al-Baqarah, verse 98. Gives the background reports and the role attributed to Mikail.
Checked by our team. For a more accurate answer to your own situation, consult a scholar. Quran translation by Sahih International. Hadith Arabic from the standard editions of the six books and the Muwatta, with gradings as recorded there; the English is our own rendering. Spotted a mistake? Tell us.