YV 4.6b

if he were to place the heart-spit on the earth, he would cause pain to the earth; if on the waters, he would cause pain to the waters; he places it in the meeting-place of dry and wet, to appease both. He should think of whomsoever he hates; verily he causes him pain. The gods divided the sacrifice on the Agnidh's altar: of what was left over they said, 'Let this remain here.' That is why the Vasativari (waters) have their name. But in the morning they could not arrange (to divide it); they placed it in the waters, they became the Vasativaris. He takes the Vasativaris; the Vasativaris are the sacrifice; verily having taken from the beginning the sacrifice he stays (with it). If the sun set, on one who has not taken (the waters), his sacrifice would not be begun [1], and he would split the sacrifice. He should either take waters with radiance in them, or having deposited gold he takes them with light in them, or he should take them from the tank of a Brahman who performs many sacrifices, for he is one who has taken the Vasativaris. He takes the Vasativaris; the Vasativaris are cattle; verily having taken cattle from the beginning he stays (with them). If he were to take them along the stream, his cattle would be likely to wander from him; he takes them standing against the stream; verily he obstructs cattle and seizes them for him. Indra [2] slew Vrtra; he died upon the waters; of them what was pure, fit for sacrifice, and divine, that was set free. They became the Vahantis. He takes of the Vahantis; verily he takes those of waters which are pure, fit for sacrifice, and divine. He should not pass over the nearest Vahantis; if he were to pass over the nearest Vahantis, he would despise the sacrifice. He should not take of stagnant (waters); the stagnant (waters) are seized by Varuna; if he were to take of stagnant (waters) [3], be would cause Varuna to seize his sacrifice.