There are a few sources that suggest the importance of reverence for holy persons. It seems, however, that in the Buddhist context the sense of 'inviolability' usually attached to the idea of blasphemy in Western culture is not present in the same way. That is, all of the passages explicitly link the action to a negative result, either in future existences or, as in the final example, in the here and now; it is the fact that they cause suffering for oneself which makes them wrong.
'Reviling the Noble Ones' is part of a list of actions that are associated with rebirth in lower realms--i.e., animal, hungry ghost, and hell realms. The opposite, not reviling the Noble Ones, is listed as one of the elements associated with favorable results:
'These beings — who were endowed with bad conduct of body, speech &
mind, who reviled noble ones, held wrong views and undertook actions
under the influence of wrong views — with the break-up of the body,
after death, have re-appeared in the plane of deprivation, the bad
destination, the lower realms, in hell. But these beings — who were
endowed with good conduct of body, speech, & mind, who did not revile
noble ones, who held right views and undertook actions under the
influence of right views — with the break-up of the body, after death,
have re-appeared in the good destinations, in the heavenly world.'
A few texts where this can be found are the Devaduta Sutta, the Potaliya Sutta (from which the above passage is taken), and the Sekha-patipada Sutta
There are also some texts that discuss the results of not being respectful:
"Here, student, some woman or man is obdurate and haughty; he does not
pay homage to whom he should pay homage, or rise up for whom he should
rise up, or give a seat to whom he should give a seat, or make way for
whom he should make way, or worship him who should be worshipped, or
respect him who should be respected, or revere him who should be
revered, or honor him who should be honored. Due to having performed
and completed such kammas, on the dissolution of the body, after
death, he reappears in a state of deprivation... If instead he comes
to the human state, he is low-born wherever he is reborn. This is the
way that leads to low birth, that is to say, to be obdurate and
haughty, not to pay homage to whom he should pay homage, nor rise up
for..., nor give a seat to..., nor make way for..., nor worship...,
nor respect..., nor revere..., nor honor him who should be honored. -- from the Cula-dammavibhanga Sutta
Further, according to the Garava Sutta, even a Buddha would suffer because of not having appropriate reverence:
I have heard that on one occasion, when the Blessed One was newly
Self-awakened, he was staying at Uruvela on the bank of the Nerañjara
River, at the foot of the Goatherd's Banyan Tree. Then, while he was
alone and in seclusion, this line of thinking arose in his awareness:
"One suffers if dwelling without reverence or deference. Now on what
brahman or contemplative can I dwell in dependence, honoring and
respecting him?" (Note: According to the text, the Buddha determines that there is no one more worthy/accomplished than he and so resolves upon revering the Dhamma.)
I hope this helps somewhat.
