‏النكاح : Hadeeth No:3270 Abu Huraira (Allaah be pleased with him) reported: I heard Allaah's Messenger (sallAllaahu alayhi wa sallam) say: Father's sister should not be combined with her brother's daughter, nor the daughter of a sister with her mother's sister....

‏الصلاة : Hadeeth No:1114 Mu'aiqib quoted the Prophet of Allaah (sallAllaahu alayhi wa sallam) mentioning the removal of pebbles from the ground where he prostrated himself. He (the Prophet) said: It you must do so, do it only once....