The following verses are from Garuda Purana, Brahma kanda, 16th Adyaya:
maNimAnnAma daityastu shaN^karAkhyo bhaviShyati |
sarveShAM saN^karaM yastu kariShyati na saMshayaH || 3:16:70
tena shaN^karanAmA.asau bhaviShyati khageshvara |
dharmAn.h bhAgavatAn.h sarvAn.h vinashyati sarvathA || 3:16:71
A Demon by name maNimAn will come into being as Shankara, who will, no doubt, pollute everything. This is why, O King of birds (Garuda), his name will be Shankara; he will pollute and destroy all BhAgavata Dharmas.
Source
vAyu purANa :-
janayiShyathi Kala: kaScinmaNimAn vidhDhipaarvathi |
praviSya thathra dhEvESa pracCannam boudhDhamEvahi ||
( Rudradeva saying to ParvathiDevi-When Demon by name Maniman will
take birth on earth in Kaliyuga, By entering in him, I will preach
Advaith Shasthra which is another form of Boudha Shsthra).
skamdha purANa :-
kAladi grAmake rudhrAvESAjjayathi mOhayan |
boudhDhaSAsthra parO viprO ya:kaSciththasya SiShyaka: ||
sasamkaraSca sanyasya thasmAthsanyAsarUpiNa : ||
vEdhAmthaSAsthramithyEthath dhuShtaSAsthram cakArayath ||
( In a Village which will be called as Kaaladi, Demon will take
birth with Rudravesha and will be a Disciple of follower of Boudha
Shastra and in disguise of a Sanyasi (Yathi) will preach
Bouddha Dharma (Dushta Shasthra) by misleadingly saying that he will teach Vedanta Shasthra.
Source
Note: Whether these puranas/verses are genuine or added later is another matter.
Bhaskara (9th Century CE), the propounder of bhedabheda-siddhanta was
one of the earliest Indian philosophers to attack Mayavada. In his
commentary on Vedanta-sutra, Bhaskara does not mention Sankara by
name, nor does he mention the name of his philosophy. However by
reviewing his arguments against the monistic doctrine of maya and the
Advaitic concept of anirvacaniya, it is obvious who and what he is
alluding to.
Bhaskara is positively vitriolic when writing about the Advaitin’s
concept of maya, referring to it’s adherents as bauddha-matavalambin
(those that cling to Buddhist ideology) and goes on to say that their
philosophy reeks of Buddhism (bauddha-gandhin). Bhaskara concludes
that, “No one but a drunkard could hold such theories” and that
Mayavada is subversive of all sastrika knowledge:
vigitam vicchinna-mulam mahayanika-bauddhagathitam mayavadam
vyavarnayanto lokan vyamohayanti
Expanding on the contradictory and baseless philosophy of maya
propagated by the Mahayanika Buddhists, the Mayavadis have misled the
whole world. (Bhaskara’s Brahma-sutra-bhasya 1.4.25)
In his Siddha-traya, the Vaisnava philosopher Yamunacarya (917–1042
CE) stated that Buddhism and Mayavada was essentially the same thing.
The only difference he could see was that while one was openly
Buddhist (prakata-saugata), the other was simply covered
(pracchana-saugata).
Following on from Yamunacarya, his disciple Sri Ramanuja (1017-1137
CE) also concurred that Mayavada was another form of Buddhism. In his
Sri Bhashya commentary on the Vedanta-sutras, Ramanuja says that to
claim that non-differentiated consciousness is real and all else is
false is the same as the Buddhist concept of universal void.
Furthermore, Ramanuja states that the concepts of such
crypto-Buddhists make a mockery of the teachings of the Vedas
(veda-vadacchadma pracchana-bauddha).
Another acarya in the line of Ramanuja, Vedanta Desika (1269–1370)
wrote his famous Sata-dusini, a text expounding one hundred flaws
found in Mayavada. In that work he refers to Sankara as a
rahu-mimamsaka (one who obscures the true meaning of Vedanta), a
bhrama-bhiksu (a confused beggar), a cadmavesa-dhari – one who is
disguised in false garb, and goes on to assert that, “By memorizing
the arguments of the Sata-dusini like a parrot, one would be
victorious over the crypto-Buddhists.”
In another work, Paramata-bhangam, Vedanta Desika refers to Sankara
as, “One who studied the Vedas in the shop of a Madhyamika Buddhist”
(referring to Sankara’s param-guru Gaudapada of whom we will speak of
later in this article).
Source