Sahih Muslim 1525
Sahih Muslim · Book 21: The Book of Transactions · It is invalid to sell goods before taking possession of them
Ibn Abbas (Allah be pleased with them) reported Allah's Messenger (ﷺ) as saying:
حَدَّثَنَا أَبُو بَكْرِ بْنُ أَبِي شَيْبَةَ ، وَأَبُو كُرَيْبٍ وَإِسْحَاقُ بْنُ إِبْرَاهِيمَ قَالَ إِسْحَاقُ أَخْبَرَنَا وَقَالَ الآخَرَانِ، حَدَّثَنَا وَكِيعٌ ، عَنْ سُفْيَانَ ، عَنِ ابْنِ طَاوُسٍ ، عَنْ أَبِيهِ ، عَنِ ابْنِ عَبَّاسٍ ، قَالَ قَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم " مَنِ ابْتَاعَ طَعَامًا فَلاَ يَبِعْهُ حَتَّى يَكْتَالَهُ " . فَقُلْتُ لاِبْنِ عَبَّاسٍ لِمَ فَقَالَ أَلاَ تَرَاهُمْ يَتَبَايَعُونَ بِالذَّهَبِ وَالطَّعَامُ مُرْجَأٌ وَلَمْ يَقُلْ أَبُو كُرَيْبٍ مُرْجَأٌ .
He who buys foodgrain should not sell it, until he has weighed it (and then taken possession of it). I (Tawus) said to Ibn Abbas (Allah be pleased with them): Why is it so? Thereupon he said: Don't you see that they (the people) sell foodgrains against gold for the stipulated time. Abu Kuraib did not make any mention of the stipulated time.