‏البيوع : Hadeeth No:3848 Abu Sa'id al-Khudri (Allaah be pleased with him) reported Allaah's Messenger (sallAllaahu alayhi wa sallam) as saying: Do not sell gold for gold and silver for silver weight for weight or of the same quality....

‏الفضائل : Hadeeth No:5683 This hadith has been narrated on the authority of Abu Sa'id Khudri through another chain of transmitters....