It is invalid to sell goods before taking possession of them
حَدَّثَنَا يَحْيَى بْنُ يَحْيَى، قَالَ قَرَأْتُ عَلَى مَالِكٍ عَنْ نَافِعٍ، عَنِ ابْنِ عُمَرَ، قَالَ كُنَّا فِي زَمَانِ رَسُولِ اللَّهِ صلى الله عليه وسلم نَبْتَاعُ الطَّعَامَ فَيَبْعَثُ عَلَيْنَا مَنْ يَأْمُرُنَا بِانْتِقَالِهِ مِنَ الْمَكَانِ الَّذِي ابْتَعْنَاهُ فِيهِ إِلَى مَكَانٍ سِوَاهُ قَبْلَ أَنْ نَبِيعَهُ .
Ibn Umar (Allah be pleased with them) reported: We used to buy foodgrains during the lifetime of Allah's Messenger (ﷺ). He (the Holy Prophet) would then send to us one who commanded us to take them (the foodgrains) to a place other than the one where we had bought them before we sold it.