"The Messenger of Allah (ﷺ) prohibited two sales in one." There are narrations on this topic from 'Abdullah bin 'Amr, Ibn 'Umar, and Ibn Mas'ud. [Abu Eisa said:] The Hadith of Abu Hurairah is a Hasan Sahih Hadith. This is acted upon according to the people of knowledge. Some of the people of knowledge have explained it by saying that two sales in one is when one says: "I will sell you this garment for ten in cash, and twenty on credit." He does not distinguish between either of the two sales. But when he distinguishes it as being one of them, then there is no harm when one of them is agreed upon. Ash-Shafi'i said: "Included in the meaning of what the Prophet (ﷺ) prohibited of regarding two sales in one, is if one said: 'I will sell you the house of mine for that (price), upon the condition that you sell me you alve for this (price). When I get the slave, then you get the house.' In this way the sales are distinguished without the prices being known, and neither of them knows what will happen at the conclusion of it (the agreement)."
حَدَّثَنَا هَنَّادٌ، حَدَّثَنَا عَبْدَةُ بْنُ سُلَيْمَانَ، عَنْ مُحَمَّدِ بْنِ عَمْرٍو، عَنْ أَبِي سَلَمَةَ، عَنْ أَبِي هُرَيْرَةَ، قَالَ نَهَى رَسُولُ اللَّهِ صلى الله عليه وسلم عَنْ بَيْعَتَيْنِ فِي بَيْعَةٍ . وَفِي الْبَابِ عَنْ عَبْدِ اللَّهِ بْنِ عَمْرٍو وَابْنِ عُمَرَ وَابْنِ مَسْعُودٍ . قَالَ أَبُو عِيسَى حَدِيثُ أَبِي هُرَيْرَةَ حَدِيثٌ حَسَنٌ صَحِيحٌ . وَالْعَمَلُ عَلَى هَذَا عِنْدَ أَهْلِ الْعِلْمِ وَقَدْ فَسَّرَ بَعْضُ أَهْلِ الْعِلْمِ قَالُوا بَيْعَتَيْنِ فِي بَيْعَةٍ . أَنْ يَقُولَ أَبِيعُكَ هَذَا الثَّوْبَ بِنَقْدٍ بِعَشَرَةٍ وَبِنَسِيئَةٍ بِعِشْرِينَ وَلاَ يُفَارِقُهُ عَلَى أَحَدِ الْبَيْعَيْنِ فَإِذَا فَارَقَهُ عَلَى أَحَدِهِمَا فَلاَ بَأْسَ إِذَا كَانَتِ الْعُقْدَةُ عَلَى وَاحِدٍ مِنْهُمَا . قَالَ الشَّافِعِيُّ وَمِنْ مَعْنَى نَهْىِ النَّبِيِّ صلى الله عليه وسلم عَنْ بَيْعَتَيْنِ فِي بَيْعَةٍ أَنْ يَقُولَ أَبِيعُكَ دَارِي هَذِهِ بِكَذَا عَلَى أَنْ تَبِيعَنِي غُلاَمَكَ بِكَذَا فَإِذَا وَجَبَ لِي غُلاَمُكَ وَجَبَ لَكَ دَارِي . وَهَذَا يُفَارِقُ عَنْ بَيْعٍ بِغَيْرِ ثَمَنٍ مَعْلُومٍ وَلاَ يَدْرِي كُلُّ وَاحِدٍ مِنْهُمَا عَلَى مَا وَقَعَتْ عَلَيْهِ صَفْقَتُهُ .
Tirmizi
The Book on Business • Hadith 1238