It is invalid to sell goods before taking possession of them
حَدَّثَنَا يَحْيَى بْنُ يَحْيَى، وَعَلِيُّ بْنُ حُجْرٍ، قَالَ يَحْيَى أَخْبَرَنَا إِسْمَاعِيلُ بْنُ جَعْفَرٍ، وَقَالَ عَلِيٌّ حَدَّثَنَا إِسْمَاعِيلُ، عَنْ عَبْدِ اللَّهِ بْنِ دِينَارٍ، أَنَّهُ سَمِعَ ابْنَ عُمَرَ، قَالَ قَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم " مَنِ ابْتَاعَ طَعَامًا فَلاَ يَبِعْهُ حَتَّى يَقْبِضَهُ " .
Ibn 'Umar (Allah be pleased with them) reported Allah's Messenger (ﷺ) as saying,: He who bought foodgrain should not sell it until he had taken possession of it.