(20) باب النَّهْىِ أَنْ يَخْطُبَ الرَّجُلُ عَلَى خِطْبَةِ أَخِيهِ .
It was narrated from Abu Hurairah that the Prophet said:
"None of you should propose marriage to a woman when someone else has already proposed to her." (ES)
Reference (ES): Sunan an-Nasa'i 3242 (ES)
In-book reference (ES): Book 26, Hadith 47 (ES)
English translation (ES): Vol. 4, Book 26, Hadith 3244 (ES)