Verse 1.2.5.26

sa hovāca | bṛhaspatirāṅgiraso yadvai śuśruma devānām pariṣūtaṃ tadeṣa yajño bhavati yacūtāni havīṃṣi kLptā vedistenāvamarśamacāriṣṭa tasmātpāpīyāṃso'bhūt tenānavamarśa yajadhvaṃ tathā śreyāṃso bhaviṣyathetyā kiyata ityā barhiṣa staraṇāditi barhiṣā ha vai khalveṣā śāmyati sa yadi purā barhihṣa staraṇātkiṃcidāpadyeta barhireva tatstṛṇannapāsyedatha yadā barhi stṛṇantyapi padābhitiṣṭhanti sa yo haivaṃ vidvānanavamarśaṃ yajate śreyānhaiva bhavati tasmādanavamarśameva yajeta

Preview of English translation:

26. Brihaspati Aṅgirasa then said, “What we have heard of as produced for the gods that is this sacrifice, that is to say, the cooked oblations and the prepared altar; therewith you have performed while touching: that is why you have become more sinful. Sacrifice therefore without touching, for thus you will become righteous!” 'How long?' they asked. “Till the spreading of the sacrificial grass (on the altar),” he said. By the sacrificial grass, namely, it (the altar) becomes appeased. If, therefore, before the spreading of the sacrificial grass anything were to fall on it, let him only remove it at the time when he spreads the sacrificial grass; for when they spread the sacrificial grass, then they also step on it with the foot. He who knowing this sacrifices without touching, becomes indeed righteous: let him therefore sacrifice, without touching (the altar and oblations).

For a detailled translation, including proper diacritics and footnotes, go the full English translation.