‏الأيمان : Hadeeth No:4057 'Adi b. Hatim reported Allaah's Messenger (sallAllaahu alayhi wa sallam) as saying: He who took an oath, but he found something else better than that, should do that which is better and break his oath....

‏الصلاة : Hadeeth No:1591 'A'isha reported: The Messenger of Allaah (sallAllaahu alayhi wa sallam) used to recite in sitting position (while observing the Tahajjud prayer) and when he intended to bow, he would stand up and recite (for the duration in which) a man (ordinarily) recites forty verses....