Sahih Muslim | Book 43 | Hadith Number 7165
Narrated by 'Aisha
'Aisha said in connection with the verse: "And if a woman has reason to fear ill-treatment from her husband or that he might turn away from her" (iv. 128) that it was revealed in case of a woman who had long association with a person (as his wife) and now he intends to divorce her and she says: Do not divorce me, but retain me (as wife in your house) and you are permitted to live with another wife. It is in this context that this verse was revealed.