Maliks Muwatta Book 29, Hadith Number 30.

Yahya related to me that Malik heard Ibn Shihab say, “When a man gives his wife the right of choice, and she chooses him, that is not divorce.”

Malik added, “That is the best of what I have heard.”

Malik said that if a woman who had been given the right of choice by her husband chose herself, she was divorced trebly. If her husband said, “But I only gave her the right of choice in one,” he had none of that. That was the best of what he had heard.

Malik said, “If the man gives his wife the right of choice and she says, ‘I accept one’, and he says, ‘I did not mean that, I have given the right of choice in all three together,’ then if she only accepts one, she remains with him in her marriage, and that is not separation if Allah, the Exalted wills.”