I agree with Sujato, here viharati simply means “he dwells”, as it almost always does in Buddhist texts. It is intended to convey that a meditator attains a particular state of nonattachment due to the cessation of sensory experience.
In order to understand what the passage is getting at, it is worth noting that the Sanskrit translation is full of mistakes and none more egregious than this one. The original Chinese was:
菩提薩埵依般若波羅蜜多故心無罣礙,無罣礙故無有恐怖遠離顛倒夢想究竟涅槃。
Since the bodhisatva relies on perfect paragnosis their mind is not attached anywhere; being detached they are not afraid, transcend illusions and delusions, and attain final extinction.
The phrase “their mind is not attached anywhere” translates xīn wú guà ài 心無罣礙. Huifeng (2014) showed that in Kumārajīva’s translations wú guà ài 無罣礙 often corresponds to Sanskrit na kvacit sajjati “his mind is not attached anywhere”. Note that sajjati is a Pāli-like Prakritism.
It seems that whoever forged the Sanskrit text had a working knowledge of Sanskrit grammar but poor vocabulary and they ended up translating this as:
bodhisatvaḥ prajñāpāramitām āśritya viharaty acittāvaraṇaś "
the bodhisatva who is without mental hindrance dwells having relied on perfect insight
This is legible but it’s inelegant and the choice of words is misleading. Note that translators all seem to want to have many hindrances, but acittāvaraṇaḥ is the nominative singular “a mental hindrance”.
What follows is supposed to be the consequence of being in this state of nonattachment, reflected in the use of gù 故 following the word. In Chinese: Wú guà ài gù 無罣礙故 “Since, [his mind] is not attached…”
In the Sanskrit Heart Sutra, this becomes cittāvaraṇa-nāstitvād “because of the non-existence of a mental hindrance” one of the weirdest phrases in the text and in all Buddhist literature. I might have expected: acittāvaraṇāt “since [he is] without a mental hindrance”; or just tena “by this” or tasmāt “because of that”. But this kind of sentence in a Buddhist text begs for an absolutive.
My revised edition will be out soon (I was expecting it some weeks ago). In it, I retranslate from Chinese into Sanskrit, attempting to use Buddhist idioms. I came up with:
yato prajñāpāramitām niśrayati tato bodhisatvacittam na kvacit sajjati asaktva atrasto viparyāsamāyāvivikito nirvāṇaparyavasānañca prāpṇoti
Since he has relied on perfect insight, the mind of the bodhisatva is not attached to anything; being detached he is unafraid, isolated from delusions and illusions, and he attains final extinction.
In other words, in keeping with other Prajñāpāramitā texts, this passage is emphasising the attainment of cessation of sense experience by someone on the bodhisatva path. It is in (or following) that state, in which all sensory experience has ceased, that we gain insight and end rebirth. This must be in part because following cessation the sense of self is suppressed and one’s actions are no longer governed by conscious volition (cetanā). Thus there are no longer karmic consequences and one is bound to be liberated once one’s old karma runs out.
In Huifeng (2014), this mistranslation becomes part of the argument for an epistemic reading of the Heart Sutra. I’ve taken that suggestion and expanded on it, though I prefer to think of it as a phenomenological reading. Here I draw heavily on the work of (the late) Sue Hamilton and her phenomenological reading of the Pāli suttas.
This is not a reference to Nāgārjuna’s metaphysics of emptiness. This is an phenomenological absence which many living meditors (not least everyone’s favourite Theravādin scholar-monk, Anālayo) can attest is a real state that one can be in.
Mahāyānists tend to find my references to Early Buddhism to explain Prajñāpāramitā confusing. But note that Anālayo has recently argued that this form of practice aimed at cessation – epitomised by the Cūḷasuññata Sutta (MN 121) – may actually predate Buddhism. I agree with this. I think prajñāpāramitā is less a late reaction to mainstream Buddhists taking up Abhidharma methods, and more a conservative “back to basics” restatement of the importance of cessation and the subsequent absence of sensory experience (aka nirvāṇa). Keep in mind that the oldest Prajñāpāramitā manuscript (1st century CE) is about 400-500 years older than the oldest Pāli manuscript (5th-6th century CE). Prajñāpāramitā was also clearly based on an existing, probably oral, tradition.