One who is in a state of purity and doubts whether he has broken it

Sayyiduna Abu Hurayrah (may Allah be pleased with him) narrates: The Prophet (peace and blessings be upon him) said: "When one of you is praying, Satan comes to him and frightens him, just as a man frightens his animals. If that person remains calm, Satan breaks wind between his buttocks so that the person's attention is diverted from his prayer. When anyone finds such a situation, let him not end the prayer until he hears the sound (of his wind passing) or perceives a smell."
Ahmad recorded it, and Abu Dawud recorded it in abridged form; the narrators of Ahmad are the narrators of the Sahih.

With the same chain, it is reported from Sayyiduna Abu Hurayrah (may Allah be pleased with him) that he said: The Prophet (peace and blessings be upon him) said: "When one of you is in the mosque, Satan comes to him and frightens him, just as a man frightens his animal; and when he remains calm before him, he either constricts him or puts a bridle on him." Sayyiduna Abu Hurayrah (may Allah be pleased with him) said: You see this situation: there is a person who is leaning (to one side), and the one who has been bridled is the one you see with his mouth open, not remembering Allah.

Sayyiduna Abdullah bin Abbas (may Allah be pleased with them both) narrates: The Prophet (peace and blessings be upon him) was asked about a man who feels during the prayer that his ablution has broken, although it has not. The Prophet (peace and blessings be upon him) said: "Satan comes to one of you while he is praying, until he opens his back passage, so the man feels as though he has incurred hadath (ritual impurity), although he has not. Whoever finds such a situation, let him not end the prayer until he hears the sound (of wind passing) with his ear or perceives its smell with his nose."
Al-Tabarani recorded it in al-Mu'jam al-Kabir, and al-Bazzar recorded something similar; the narrators of this narration are the narrators of the Sahih.

Sayyiduna Abu Sa'id al-Khudri (may Allah be pleased with him) reports that the Prophet (peace and blessings be upon him) said: "Satan comes to one of you while he is praying and pulls a hair near his back passage, so the man feels as though he has incurred hadath (ritual impurity). (Such) a man should not end the prayer until he hears the sound (of wind passing) or perceives a smell."
Abu Ya'la recorded it, and Ibn Majah recorded it in abridged form; its chain contains a narrator, Ali bin Zayd, about whose use as evidence there is disagreement.

Muhammad bin Amr bin Ata says: I saw Sayyiduna al-Sa'ib bin Khabbab (may Allah be pleased with him) smelling his garment, so I asked: What is the reason for this? May Allah Almighty have mercy on you! He replied: I heard the Prophet (peace and blessings be upon him) say: "Ablution becomes necessary upon (perceiving) the smell (of passed wind, or) hearing (its sound)."
Al-Tabarani recorded it in al-Mu'jam al-Kabir; its chain contains a narrator, Abd al-Aziz bin Ubaydullah, who is da'if al-hadith (weak in hadith), and I have not seen anyone declare him trustworthy. And Allah knows best.

Sayyiduna Abdullah bin Mas'ud (may Allah be pleased with him) says: Satan comes to a person during his prayer and takes hold of a hair from his rear, so the man feels that he may have broken his ablution. (In such a situation) the man should not end his prayer until he hears a sound (of passed wind) or perceives a smell.
Al-Tabarani recorded it in al-Mu'jam al-Kabir; its chain contains a narrator, al-Hajjaj bin Artah, who is thiqah (trustworthy) but a mudallis, and (in this narration too) he did not explicitly state that he heard it.

Sayyiduna Abdullah bin Mas'ud (may Allah be pleased with him) says: Satan circles around a man during his prayer in order to spoil his prayer for him. When the man wears him out, he blows into the man's rear (so that the man feels he may have broken his ablution). When any of you senses something like this, he should not end his prayer until he perceives a smell or hears a sound.
Al-Tabarani recorded it; its narrators have been declared trustworthy.

Wa'il bin Dawud has narrated from Ibrahim al-Nakha'i this statement of Sayyiduna Abdullah bin Mas'ud (may Allah be pleased with him): "Ablution is required because of what comes out (of the body), not because of what goes in; and the fast (is broken by what) goes in (to the body), not by what comes out."
Al-Tabarani recorded it in al-Mu'jam al-Kabir, and its narrators have been declared trustworthy.