"The Three Little Men in the Wood" or "The Three Little Gnomes in the Forest" is a German fairy tale collected in 1812 by the Brothers Grimm.
A woman offers her hand in marriage to a widower: in return, her daughter would wash and drink water, and the man's would wash with milk and drink wine. After performing a test to determine his choice, he marries the woman, who keeps her word. However, by the second day of marriage, both daughters bathe and wash with water. By the third, the man's daughter washes with and drinks water, while the woman's daughter drinks wine and washes with milk. It remains this way afterwards, because the woman secretly hates her step-daughter due to her being prettier than her own…