(355) Chapter: Prohibition of Malpractices in Commerce

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]

Commentary: We learn from this Hadith that if a man knows that such and such person has asked some woman for marriage and she has accepted the proposal then he should not make an offer of marriage to her. But if the matter has ended and the first proposal permits him to try his luck then he can make a proposal to her for marriage. On the same analogy, it is prohibited for a woman to send a proposal of marriage to a man with whom some woman is already negotiating or has already negotiated.