Skandapurana 5.236.29

5.236.29

cāturmāsye viśeṣeṇa janmakaṣṭādināśanam ..
harireva vratādgrāhyo vrataṃ dehena kārayet ..
deho'yaṃ tapasā śodhyaḥ supte deve taponidhau .. 29 ..

Especially during the Cāturmāsya, the destruction of the miseries of birth and the like [occurs]; / Hari alone is to be attained through vows; one should perform the vow with one's body. / This body must be purified by austerity while the Lord, the treasure of austerity, is asleep.