It is narrated from Ibn Abbas (may Allah be pleased with him), he said: "I bear witness that Allah Almighty has declared the sale of Salam (advance payment for deferred delivery) for a fixed term permissible in His Book and has also granted permission for it." Then he recited this verse: "O you who believe! When you contract a debt for a fixed term..." (__QUR_N__: Al-Baqarah: 282)
Hadith Referenceمسند الإمام الشافعي / كتاب البيوع / 1437
Hadith Takhrijاخرجه عبد الرزاق، رقم : 14064 - والبيهقي: 6 / 19 ، 18 - وفى المعرفة السنن والآثار له (3558) - ابن ابی شيبة (22312) وصححه الحاكم : (2/ 86)۔