الأحد
كلمة (الأحد) في اللغة لها معنيانِ؛ أحدهما: أولُ العَدَد،...
Extremism in worship, abandoning the worldly life, and refraining from mixing with people.
"Rahbaaniyyah" (monasticism) is an approach of worship that is marked by extremism. It is based upon abandoning the worldly life with its pleasures, practicing asceticism, and secluding oneself from the people. Among the manifestations of monasticism is locking oneself up in a hermitage or cave or the like, wearing black clothes, abandoning the worldly life and its desires, such as marriage and so on.
"Rahbaaniyyah": fear, dread, panic. In common usage, it means withdrawing from mixing with people to dedicate oneself to worship.
To abandon the pleasures of life, considering them trivial and to isolate oneself from people.