Being thirsty one night, the King entered the arena of sacrifice, and when he saw all the brāhmaṇas lying down, he personally drank the sanctified water meant to be drunk by his wife.
Srimad Bhagavata Purana
श्रीमद्भागवतमहापुराणम्
मूल श्लोकः
राजा तद्यज्ञसदनं प्रविष्टो निशि तर्षितः । दृष्ट्वा शयानान् विप्रांस्तान् पपौ मन्त्रजलं स्वयम्
rājā tadyajñasadanaṃ praviṣṭo niśi tarṣitaḥ | dṛṣṭvā śayānān viprāṃstān papau mantrajalaṃ svayam
SB 9.6.27