Manusmriti

siva.sh/manusmriti/6/33

वनेषु च विहृत्यैवं तृतीयं भागमायुषः । चतुर्थमायुषो भागं त्यक्वा सङ्गान् परिव्रजेत् ॥ ३३ ॥

sanskrit

But having thus passed the third part of (a man’s natural term of) life in the forest, he may live as an ascetic during the fourth part of his existence, after abandoning all attachment to worldly objects.

english translation

vaneSu ca vihRtyaivaM tRtIyaM bhAgamAyuSaH | caturthamAyuSo bhAgaM tyakvA saGgAn parivrajet || 33 ||

hk transliteration by Sanscript