sacred book

Encore de Saki (more Saki).

'May I ask if you are governed by any laws of conduct whatever?'
'There are certain fixed rules that one observes for one's own comfort. For instance, never be flippantly rude to any inoffensive, grey-bearded stranger that you may meet in pine forests of smoking-rooms on the Continent. It always turns out to be the King of Sweden.'
'... When I was younger, boys of your age used to be nice and innocent.'
'Now we are only nice ... Which reminds me of a man I read of in some sacred book who was given a choice of what he most desired. And because he didn't ask for titles and honours and dignities, but only for immense wealth, these other things came to him also.'
'I am sure you didn't read about him in any sacred book.'
'Yes; I fancy you will find him in Debrett.'