One night, Caliph Umar as usual went in disguise with his companion Ibn Abbas to see the condition of the people. They strolled from one quarter to another. At last they came to a colony where poor people lived.
While passing by a small house, the Caliph heard a whispering talk within. The mother was telling her daughter that the amount of milk fetched by her for sale that day was very little. She told her that when she was young, and used to sell milk, she always mixed water with milk, and that led to considerable profit. She advised her daughter to do the same.
The girl said, “You adulterated milk, when you were not a Muslim. Now that we are Muslims, we cannot adulterate milk.” The mother said that Islam did not stand in the way of adulteration of milk. The daughter said, “Have you forgotten the Caliph’s order? He wants that the milk should not be adulterated.” The mother said, “But the Caliph has forgotten us. We are so poor, what else should we do but adulterate milk in order win bread?” The daughter said “Such a bread would not be lawful, and as a Muslim I would not do anything which is against the orders of the Caliph, and whereby other Muslims are deceived.”
The mother said, “But there is neither the Caliph nor any of his officers here to see what we do. Daughter you are still a child. Go to bed now and tomorrow I will myself mix the milk with water for you.” The girl refused to fall in with the plan of her mother. She said, “Caliph may or may not be here, but his order must be obeyed. My conscience is my Caliph. You may escape the notice of the Caliph and his officers, but how can we escape the notice of Allah and our own conscience.” Thereupon the mother remained quiet. The lamp was extinguished and the mother and the daughter went to sleep.