It is well known that Ayers rock in Australia is sacred to the Aboriginals. Australia has come up with a ban on tourists climbing the rock in order preserve its sanctity. As an idiom it means abstaining from something due to moral reasons.
Example: Adultery for many is not an Ayers rock.
Christ proclaimed the Ayers rock when he said: ‘if your eye causes you to sin, pluck it out.’
Hindu devotees to Shabrimala practice the Ayers rock before their embarkation.