أَخْبَرَنَا قُتَيْبَةُ، قَالَ حَدَّثَنَا غُنْدَرٌ، عَنْ هِشَامٍ، عَنْ مُحَمَّدٍ، عَنْ أَبِي هُرَيْرَةَ، عَنِ النَّبِيِّ صلى الله عليه وسلم قَالَ ‏
"‏ لاَ يَخْطُبْ أَحَدُكُمْ 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."