'Uqbah bin 'Amir (May Allah be pleased with him) said:
The Messenger of Allah ﷺ said, "A Mu'min is the brother of another Mu'min; and thus it is not permissible for a Mu'min to make an offer while the offer of his brother is pending, nor should he make a proposal of marriage while that of his brother is pending till he withdraws his proposal."

[Muslim].

وعن عقبة بن عامر أن رسول الله ﷺ قال:
"المؤمن أخو المؤمن، فلا يحل لمؤمن أن يبتاع على بيع أخيه ولا يخطب على خطبة أخيه حتى يذر" ((رواه مسلم)).