A Jew said to someone, ‘I shall teach you magic with the condition that you will not do any good deed.’ That individual could not learn the magic within the agreed number of days. The Jew said: ‘You must have done some good deed during these days, and due to which you could not learn the magic.’
The man said, ‘I did not perform any good deed except that I picked up a thorn from the pathway.’
The Jew remarked, ‘Yes, this is why you have not been able to learn the magic.’
Then the man said, ‘It is a great mercy of the Almighty God that I am saved from committing a great sin by doing a very small virtue.’
(Malfuzat, Vol. 6, p. 26)