‏البيوع : Hadeeth No:3667 Ibn Umar (Allaah be pleased with them) reported Allaah's Messenger (sallAllaahu alayhi wa sallam) as saying: Do not buy fruit until its good condition becomes clear, and (the danger) of blight is no more. He said: Its good condition becoming clear implies that it becomes red or yellow....

‏الأيمان : Hadeeth No:4040 Ibn 'Umar heard Allaah's Messenger (sallAllaahu alayhi wa sallam) as saying: He who has to take an oath, he must not take oath but by Allaah. The Quraish used to take oath by their fathers. So he (the Prophet) said: Do not take oath by your fathers....