Hazrat Abu Saeed (may Allah be pleased with him) narrates that wheat, barley, and unhusked barley should not be sold through Salam (forward sale) until they are husked; grapes and olives, etc., should not be sold until they become sweet; likewise, cash gold should not be sold for deferred silver, nor deferred silver for cash gold.
Hadith Referenceمسند احمد / مسند المكثرين من الصحابة / 11111
Hadith Gradingحکم دارالسلام:إسناده ضعيف لضعف ابن الهيعة .