مِشْكَاةُ الْمَصَابِيحِ
Mishkat al-Masabih 2851
Business Transactions
Business Transactions which are Forbidden - Section 1
وَعَنْ أَبِي هُرَيْرَةَ أَنَّ رَسُولَ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ قَالَ: «لَا يَسُمِ الرَّجُلُ على سَوْمِ أخيهِ الْمُسلم» . رَوَاهُ مُسلم
Abu Huraira reported God’s Messenger as saying, “A man must not offer a price above that offered by his brother Muslim.” Muslim transmitted it.
Mishkat al-Masabih, 2851صَحِيح (الألباني)