Musnad Ahmad 30:981

Hashim narrated to us, Ayyub narrated to us, from Abu Kathir, from Abu Hurairah, who said: The Messenger of Allah (peace and blessings of Allah be upon him) said: "A man shall not enter into a transaction over the transaction of his brother, nor shall he propose to a woman over the proposal of his brother. And a woman shall not stipulate the divorce of her sister [in faith] in order to empty her plate, for she shall only have what Allah, the Almighty and Majestic, has written for her."