‏الزهد والرقائق‏ : Hadeeth No:7132 The son of Abu Said al-Khudri reported on the authority of his father that Allaah's Messenger (sallAllaahu alayhi wa sallam) said. When one of you yawns while engaged in prayer, he should try to restrain so far as it lies in his power, since it is the Satan that enter therein....

‏الصيام : Hadeeth No:2426 Ibn 'Umar (Allaah be pleased with both of them) said that the Prophet of Allaah (sallAllaahu alayhi wa sallam) forbade uninterrupted fasting. They (some of the Companions) said: You yourself fast uninterruptedly, whereupon he said: I am not like you. I am fed and supplied drink (by Allaah)....