question about Shankara (quotation source)

[Aklujkar]

 Madhav Deshpande wrote:
> I would like to know
the source of two quotations.  The first one reads: zankaraH zankaraH
sAkshAd vyAso nArAyaNo hariH.  The second reads: caturbhiH saha zishyais
tu zankaro'vatarishyati.  These occur as citations in a text that I am
currently translating.  I have not been able to find their source.  The
second quotation is qualified with iti ArshavAkyAt.  This probably refers
to a Purana as its source.<

Lines very similar to the second quotation occur in
;Sriimaccha:nkara-digvijaya (1.42cd-43ab) attributed to Maadhava or
Vidyaara.nya: caturbhi.h sahita.h ;si.syai;s caturair harivad bhujai.h /
yatiindra.h ;sa:nkaro naamnaa bhavi.syaami mahii-tale //  A first person
form, bhavi.syaami is used here because god ;Sa:nkara is the speaker.

As the various ;Sa:nkara-vijayas overlap with each other in content, a line
exactly or more
similar to the one MD is trying to trace may exist in one of them.

Of MD's first quotation, the reading I remember is naaraaya.na.h svayam,
that is svaya.m in place of hari.h, which avoids redundancy and balances
saak.saat. The second line went something like tayos tu vigrahe praapte na
jaane ki.m karomy aham.