‏البيوع : Hadeeth No:3622 Ibn Umar (Allaah be pleased with them) reported that Allaah's Messenger (sallAllaahu alayhi wa sallam) forbade the outbidding (against another)....

‏الزكاة : Hadeeth No:2143 Jabir b. Abdullah reported Allaah's Messenger (sallAllaahu alayhi wa sallam) as saying: A tenth is payable on what is watered by rivers, or rains, and a twentieth on what is watered by camels....