It was narrated that Jabir said:"The Messenger of Allah ruled that pre-emption is to be given in everything that is shared in which the division is not clear, whether it is a house or a garden. It is not permissible to sell it before informing one's partner, who may take it or leave it, as he wishes. He (the share-owner) sells it without informing him, and then he has more right to it

English translation · Sunan an-Nasa'i