[Machine] On the authority of the Messenger of Allah ﷺ , he said: "Whoever buys food should not sell it until he measures it." So, I asked Ibn Abbas, why? He said: "Don't you see them trading gold while food is in abundance?"  

عَنْ رَسُولِ اللهِ ﷺ قَالَ مَنِ ابْتَاعَ طَعَامًا فَلَا يَبِعْهُ حَتَّى يَكْتَالَهُ فَقُلْتُ لِابْنِ عَبَّاسٍ لِمَ؟ قَالَ أَلَا تَرَاهُمْ يَتَبَايَعُونَ الذَّهَبَ وَالطَّعَامُ مُرْجَأٌ؟  

The Messenger of Allah ﷺ forbade to sell grain which one buys by measurement until one receives it in full. (Using translation from Abū Dāʾūd 3495)   

أَنَّ رَسُولَ اللهِ ﷺ نَهَى أَنْ يَبِيعَ أَحَدٌ طَعَامًا اشْتَرَاهُ بِكَيْلٍ حَتَّى يَسْتَوْفِيَهُ