Shiva Purana

siva.sh/siva-purana/uma-samhita/26/24

सुश्वासेन सुशय्यायां योगं युंजीत योगवित् ।। दीपं विनांधकारे तु प्रजाः सुप्तेषु धारयेत् ।। २४।।

sanskrit

The knower of Yoga shall practise it taking breath normally sitting on a good bed. If he practises in darkness he shall not keep any lamp. He shall practise when people are asleep.

english translation

suzvAsena suzayyAyAM yogaM yuMjIta yogavit || dIpaM vinAMdhakAre tu prajAH supteSu dhArayet || 24||

hk transliteration by Sanscript