I heard a Shaykh saying that the Companions, may Allaah be pleased with them, used to be knights during the day and monks at night. However, I heard another Shaykh saying that there is no monasticism in Islam. How can these two sayings be reconciled?

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 is no contradiction between the two sayings because describing the Companions as monks during the night means that they did many acts of worship during the night and devoted themselves to Allaah by reciting the Quran, supplicating and shedding tears. Consequently, their status resembles that of monks because of their  continuous worship.

As for prohibited monasticism in Islam, this is that which leads a person to abandoning their worldly affairs and being completely devoted to worship. Indeed, sometimes it may lead to prohibiting some permissible things to perform this worship. Anas narrated that three men during the lifetime of the Prophet, sallallaahu ‘alayhi wa sallam, wanted to go to extremes in worship by refraining from what is lawful.  One of them wanted to spend the whole night performing voluntary prayer for the rest of his life, the other wanted to fast everyday for the rest of his life, and the third wanted to remain celibate and not marry for the rest of his life. The Prophet, sallallaahu ‘alayhi wa sallam, forbade them from doing so, telling them that he feared and worshipped Allaah The Almighty the most even though he did all that they had resolved to give up, and still his way is the best way. Then he disassociated himself from all those who do not follow his path, thinking that there is a better way. [Al-Bukhari and Muslim]

Allaah Knows best.