I want to ask that : what is sadhu? Are there any parameters defined for that. Are they need to be Vairagi? What is the difference between Sadhu And Sajjan? I mean to ask Sadhu is Derived from sadhana (possibly I may be wrong) so to become a sadhu is it must become a vai ragi or it means whatever life you live (you can marry and have a family) but you are a true devotee and disciplined? I mean the Srimad Bhagwat Geeta's Teaching That Work Is Workship
Basic meaning of Sadhu and Vairagi is someone who is a complete renunciate, for whom everything on and including earth belongs to them, yet they own nothing. Sajjan means a virtuous person who takes care to always follow the path of righteousness, but they have not necessarily renounced possessions. Mahadev is the greatest Sadhu / Vairagi. Saints are said to be sajjan. Even a common man can be sajjan if he chooses. But it is not easy to be a complete renunciate. - source: various chapters of Mahabharat Book 12 Mokshadharma Parva.