‏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....

‏الزكاة : Hadeeth No:2239 Abu Huraira reported Allaah's Messenger (sallAllaahu alayhi wa sallam) assaying: If anyone contributes a pair of anything for the sake of Allaah, he would be invited to enter Paradise (with these words): O servant of Allaah. it is good (for you). These who engage in prayer will he invited to enter b...