عن أنس رضي الله عنه قال‏:‏ نهى رسول الله صلى الله عليه وسلم أن يبيع حاضر لباد وإن كان أخاه لأبيه وأمه‏.‏ ‏(‏‏(‏متفق عليه‏)‏‏)‏‏.‏

Ibn 'Umar (May Allah be pleased with them) said

The Messenger of Allah (ﷺ) said, "A person should not enter into a transaction when his (Muslim) brother has already negotiated, nor should he make a proposal of marriage when that of his brother is pending, except with the permission of the latter."[Al-Bukhari and Muslim]