‏النكاح : Hadeeth No:3409 Ibn Abbas (Allaah be pleased with them) reported: It was proposed that he (the Prophet) be married to the daughter of Hamza, whereupon he said: She is not lawful for me for she is the daughter of my foster-brother, and that is unlawful by reason of fosterage what is unlawful by reason of genealogy....

‏البيوع : Hadeeth No:3653 Jabir b. Abdullah (Allaah be pleased with them) reported Allaah's Messenger (sallAllaahu alayhi wa sallam) as saying: When you purchase foodgrains, do not sell them until you have taken possession of them....