The Prophet ﷺ said, "None of you should sell over the sale of another, nor propose marriage over the marriage proposal of another."
حدثنا قتيبة حدثنا الليث عن نافع
عن النبي ﷺ قال لا يبع بعضكم على بيع بعض ولا يخطب بعضكم على خطبة بعض
Agreed upon [by Bukhari and Muslim]. Muslim also narrated it in the Book of Marriage, chapter on the prohibition of proposing marriage to a woman already proposed to by one's brother until he permits it or withdraws, hadith no. 1412, from the hadith of Layth bin Saad, and Bukhari, hadith no. 2165, from the hadith of Nafi with the same wording.On this subject there is also a hadith from Abu Hurairah [Ahmad 2/311, 318] and from Samura [Ahmad 5/11].