حَدَّثَنَا إِسْحَاقُ بْنُ عِيسَى، أَنْبَأَنَا مَالِكٌ، عَنْ نَافِعٍ، عَنِ ابْنِ عُمَرَ
رَضِيَ اللَّهُ عَنْهُ قَالَ كُنَّا نَتَبَايَعُ الطَّعَامَ عَلَى عَهْدِ رَسُولِ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ فَيَبْعَثُ عَلَيْنَا مَنْ يَأْمُرُنَا بِنَقْلِهِ مِنْ الْمَكَانِ الَّذِي ابْتَعْنَاهُ فِيهِ إِلَى مَكَانٍ سِوَاهُ قَبْلَ أَنْ نَبِيعَهُ
We used to buy and sell foodstuff at the time of the Messenger of Allah (sallallahu alayhi wa sallam), and he would send someone to tell us to transfer the food from the place we have bought it to another place before selling it.
Musnad Ahmad 373, Book 3, The Hadeeth of Saqeefah, Hadith 5. 1 min read