Manusmriti

siva.sh/manusmriti/6/23

ग्रीष्मे पञ्चतपास्तु स्याद् वर्षास्वभ्रावकाशिकः । आर्द्रवासास्तु हेमन्ते क्रमशो वर्धयंस्तपः ॥ २३ ॥

sanskrit

In summer let him expose himself to the heat of five fires, during the rainy season live under the open sky, and in winter be dressed in wet clothes, (thus) gradually increasing (the rigour of) his austerities.

english translation

grISme paJcatapAstu syAd varSAsvabhrAvakAzikaH | ArdravAsAstu hemante kramazo vardhayaMstapaH || 23 ||

hk transliteration by Sanscript