SB 9.6.27
raja tad-yajña-sadanam
pravisto nisi tarsitah
drstva sayanan viprams tan
papau mantra-jalam svayam
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
Being thirsty one night, the King entered the arena of sacrifice, and when he saw all the brahmanas lying down, he personally drank the sanctified water meant to be drunk by his wife.
Purport by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
Yajñas performed by brahmanas 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 brahmanas 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.