'The Messenger of Allah (ﷺ) forbade selling food bought by measure until two Sa' have been measured - the Sa' of the seller and the Sa' of the buyer."
Sunan Ibn Majah Book 12, Hadith 92
← Previous Hadith "The Messenger of Allah (ﷺ) said: 'Whoever buys food, let him not sell it until he has taken full possession of it.'" (Sahih) In his narration, (one of the narrators) Abu 'Awanah said: "Ibn 'Abbas said: 'I think everything is like food."'

Sunan Ibn Majah Book 12, Hadith 91 Next Hadith → "We used to buy food from troops of riders (i.e., the caravans) without knowing the amount, but the Messenger of Allah (ﷺ) forbade us to sell it until it had been delivered to us."

Sunan Ibn Majah Book 12, Hadith 93