The Holy Prophet was once requested by an aged woman to speak to her son, who spent all his daily wage on dates, leaving her penniless. The Prophet promised to do so after five weeks’ interval.
On the appointed day the boy was brought before the Prophet, who spoke to him very kindly, saying, “You are such a sensible lad that you ought to remember that your mother has endured much suffering for your sake, sacrificing all her wages in order to bring you up. And now she is so old and you are in a position to support her, and you are squandering your money on dates. Is this just or right? I hope by the grace and mercy of Allah you will give up this habit.” The boy listened very attentively and profited by what he heard.
But the disciples of the Prophet wondered, and asked why the reproof was delayed for thirty-five days. The Holy Prophet explained, saying, “I myself am fond of dates, and I felt that I had no right to advise the lad to abstain from them until I had myself refrained from eating them for five weeks.”
The healer of character should never for a single moment try to heal another of weaknesses to which he is himself addicted.
from The Sufi Message series, vol IV, Health, Mental Purification and the Mind World, pt. II, chap. 5