Mulla Nasrudin

Once bitten

   A man borrowed some money from Nasrudin. The Mulla thought
that he would never get it back, but gave the money nevertheless.
   Much to his surprise, the loan was promptly repaid. Nasrudin brooded.
   Some time later the same man asked for the loan of a further sum, 
saying: ‘You know my credit is good. I have repaid you in the past.’
   ‘Not this time, you scoundrel!’ roared Nasrudin. ‘You deceived me
the last time when I thought that you would not return the money. You
won’t get away with it a second time.’