I found the source of the verse I was looking for. The following verse:
na vadet yaavaniim bhaa.saam praa.nai.h ka.n.thagatair api /
gajair aapii.dyamaano 'pi na gacchej jainamandiram //
is found in the Bhavi.syapuraa.na, Pratisargaparvan, Adhyaaya 28, verse
53, p. 520, Venkateshwar Press Edition, Bombay 1959.
Madhav Deshpande