YV 6.3e

In that he offers (the offering) in four parts, he delights the metres, and they delighted by him carry the offering to the gods. The Angirases were the last to go hence to the world of heaven. The Rsis came to the place of sacrifice; they [2] saw the sacrificial cake creeping about, having become a tortoise. They said to it, 'Be firm for Indra; be firm for Brhaspati: be firm for the All-gods.' It did not become firm. They said to it, 'Be firm for Agni.' It became firm for Agni. In that (the cake) for Agni on eight potsherds is unmoved at the full and at the new moon, (it serves) to conquer the world of heaven. They said to it, 'How hast thou been left?' 'I have not been anointed', he said, 'just as an axle not anointed [3] goes wrong, so I have gone wrong.' After anointing it above, he anoints it below, to gain the world of heaven. He spreads (the cake) on all the fragments; so many cakes does he conquer in yonder world. That which is burnt belongs to Nirrti, that which is not cooked to Rudra, that which is cooked to the gods. Therefore one should cook it, without burning it, for the gods. He covers it with ashes; therefore the bones are clothed with flesh. He covers it with the bunch of grass; therefore [4] the head is covered with hair. The offering which is cooked without being sprinkled has fallen from this world, but has not reached the world of the gods. He sprinkles it before covering it; verily he makes it go among the gods. If one fragment were lost, one month of the year would be omitted, and the sacrificer would perish. If two were lost, two months of the year would be omitted, and the sacrificer would perish. He counts before covering, to guard the sacrificer [5]. If it be lost, be should make an offering on two potsherds to the Açvins, and on one potsherd to sky and earth. The Açvins are the physicians of the gods; verily by them he heals it.