MONASTICISM Arabic rahbaniyah رهبانية
ًas forbidden by Muhammad. It is related in the Traditions that ‘Usman ibn Maz’un came to the Prophet with the request that be might retire from society and become a monk (rahib). The Prophet replied, “The retirement which becomes my people is to sit in the corner of a mosque and wait for the time of prayer.” (Mishkat, book iv. ch. 8.)
In the Qnr’an, the Christians are charged with inventing the monastic life. Surah lvii. 27; “We gave them the Gospel, and we put into the hearts of those who follow him, kindness and compassion; but as to the monastic life, they invented it themselves.”
According to the Hidayah (vol. ii. p. 215), capitation tax is not to be imposed upon Rahibs, whether Christian or Pagan, but this is a matter of dispute.

Based on Hughes, Dictionary of Islam