(20) باب النَّهْىِ أَنْ يَخْطُبَ الرَّجُلُ عَلَى خِطْبَةِ أَخِيهِ .
Narrated Ibn 'Umar:
It was narrated from Ibn 'Umar that the Prophet said: "None of you should propose marriage to a woman when someone else has already proposed to her."
Reference: Sunan an-Nasa'i 3238
In-book reference: Book 26, Hadith 43
English translation: Vol. 4, Book 26, Hadith 3240