The Messenger of Allah ﷺ said, "Whoever buys food should not sell it until he has taken full possession of it."
حدثنا إسحاق بن عيسى أخبرنا مالك عن نافع
قال رسول الله ﷺ من ابتاع طعاما فلا يبعه حتى يستوفيه
Its isnad is sahih, see 2145, 2645.