Srimad-Bhagavatam: Canto 9 - Chapter 1 - Verse 27

Sanskrit:

राजा तद् यज्ञसदनं प्रविष्टो निशि तर्षित: ।द‍ृष्ट्वा शयानान् विप्रांस्तान् पपौ मन्त्रजलं स्वयम् ॥ २७ ॥

ITRANS:

rājā tad-yajña-sadanaṁpraviṣṭo niśi tarṣitaḥdṛṣṭvā śayānān viprāṁs tānpapau mantra-jalaṁ svayam

Translation:

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.

Purport:

Yajñas performed by brāhmaṇas according to Vedic ritualistic ceremonies are so potent that the sanctifying of water by Vedic mantras can bring about the desired result. In this instance, the brāhmaṇas sanctified the water so that the King’s wife might drink it in the yajña, but by providence the King himself went there at night and, being thirsty, drank the water.