Śatapatha Brāhmaṇa ("of a hundred paths") 6.7.4.14

6.7.4.14

sa yadi viṣṇukramīyamahaḥ syāt | viṣṇukramānkrāntvā vātsapreṇopatiṣṭhetātha yadi vātsaprīyaṃ vātsapreṇopasthāya viṣṇukramānkrāntvā vātsapramantataḥ kuryānna viṣṇukramānantataḥ kuryādyathā prayāya na vimuñcettādṛktadatha yadvātsapramantataḥ karoti pratiṣṭhā vai vātsapraṃ yathā pratiṣṭhāpayedavasāyayettādṛktattasmādu vātsapremevāntataḥ kuryāt

Now early on the day on which he may intend to combine them, when the sun has risen, he first throws out the ashes (from the pan); having thrown out the ashes, he releases his speech; having released his speech, he puts on a kindling-stick; having put on a kindling-stick, he takes the ashes down to (and throws them into) the water. In the same way as he takes them down he returns after taking some of the ashes; and having thrown it into the pan he stands reverentially by the fire. He then performs two expiations.