It is narrated from Sayyiduna Ibn Umar (may Allah be pleased with them both) that the Messenger of Allah (peace and blessings be upon him) said: "Whoever buys grain by measure or by weight, he should not sell it further until he has taken possession of it."
Hadith Referenceمسند احمد / مسند المكثرين من الصحابة / 5900
Hadith Gradingحکم دارالسلام:حديث صحيح، وهذا إسناد ضعيف لضعف ابن لهيعة.