The Discourse about Those with Knotted Hair

Thus I heard: At one time the Gracious One was dwelling near Gayā, on Gayā Peak. Then at that time many knotted-haired ascetics, in the cold Winter nights, in between ‘the eights’, at the time of the snowfall, in the Gayā river, were plunging out, and plunging in, were plunging out and in, were sprinkling water, and were offering the fire sacrifice, thinking: “Through this there is purity.”
The Gracious One saw that those many knotted-haired ascetics, in the Winter nights, in between ‘the eights’, at the time of the snowfall, in the Gayā river, were plunging out and plunging in, were plunging out and in, were sprinkling water, and were offering the fire sacrifice, thinking: “Through this there is purity.”
Then the Gracious One, having understood the significance of it, on that occasion uttered this exalted utterance:

“Not through water is there purity—many people bathe here!
In whom there is truth and Dhamma, he is pure, and he is a brāhmaṇa.”