Sahih Muslim
Sahih Muslim Book 009, Hadith Number 3502.
Hadith Section/Book: Sahih Muslim Sahih Muslim Book 09. Divorce
Chapter: Mere giving of option of divorce to women does not make divorce effective, but when it is really intended.
'Aisha reported that Allah's Messenger (may peace be upon him) gave option to his wives, but it was not a divorce.