Sunan Ibn Majah 1868
سنن ابن ماجه#1868SahihIt was narrated from Ibn Umar that:the Messenger of Allah said: “A man should not propose to a woman to whom his brother has already proposed.”
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Al-AlbaniSahih
Muhammad Fouad Abd al-BaqiSahih
Shuaib Al ArnautSahih
Zubair Ali ZaiSahih Muslim
In-book reference: 9:24