Matsyapurana 145.22

145.22

varṇāśrameṣu yuktasya sukhodarkasya svargatau
śrautasmārto hi yo dharmo jñānadharmaḥ sa ucyate //

The dharma of the people devoted to Varṇāśrama in accordance with the Śrutis and Smṛtis and leading to Heaven is named jñāna dharma The Brahmachāri given to good conduct and Āchāra and to do good to the preceptor (guru) performs divine functions, hence, the householder is known as "Sādhu" Those ascetics who reside in the forest and are in the third order of religious life are known also as Sādhus—22 24