Maliks Muwatta Book 29, Hadith Number 62.

Section : Idda of Divorce and Divorce of Menstruating Women.

Yahya related to me from Malik from Yahya ibn Said from a man of the Ansar that his wife asked him for a divorce, and he said to her, “When you have had your period, then tell me.” When she had her period, she told him. He said, “When you are purified then tell me.” When she was purified, she told him and he divorced her.

Malik said, “This is the best of what I have heard about it.”