Ibn Umar (Allah be pleased with them) reported Allah's Messenger (ﷺ) as having said this:

None amongst you should outbid another in a transaction, nor should he make proposals of marriage upon the proposal made by someone else.

وَحَدَّثَنَا قُتَيْبَةُ بْنُ سَعِيدٍ، حَدَّثَنَا لَيْثٌ، ح وَحَدَّثَنَا ابْنُ رُمْحٍ، أَخْبَرَنَا اللَّيْثُ، عَنْ نَافِعٍ، عَنِ ابْنِ عُمَرَ، عَنِ النَّبِيِّ صلى الله عليه وسلم قَالَ ‏

‏ لاَ يَبِعْ بَعْضُكُمْ عَلَى بَيْعِ بَعْضٍ وَلاَ يَخْطُبْ بَعْضُكُمْ عَلَى خِطْبَةِ بَعْضٍ ‏

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