Read all Ahadith in the book of as-sahw (forgetting) by sahih al bukhari

Narrated `Abdullah bin Buhaina: Allah's Apostle once led us in a prayer and offered two rak`at and got up (for the third rak`a) without sitting (after the second rak`a). The people also got up with him, and when he was about to finish his prayer, we waited for him to finish the prayer with Taslim but he said Takbir before Taslim and performed two prostrations while sitting and then finished the prayer with Taslim.

Narrated `Abdullah bin Buhaina: Allah's Apostle got up after the second rak`a of the Zuhr prayer without sitting in between (the second and the third rak`at). When he finished the prayer he performed two prostrations (of Sahu) and then finished the prayer with Taslim.

Narrated' `Abdullah: Once Allah's Apostle offered five rak`at in the Zuhr prayer, and somebody asked him whether there was some increase in the prayer. Allah's Apostle said, What is that? He said, You have offered five rak`at. So Allah's Apostle performed two prostrations of Sahu after Taslim.

Narrated Abu Huraira: The Prophet led us in the `Asr or the Zuhr prayer and finished it with Taslim. Dhul-Yadain said to him, O Allah's Apostle! Has the prayer been reduced? The Prophet asked his companions in the affirmative. So Allah's Apostle I offered two more rak`at and then performed two prostrations (of Sahu). Sa`d said, I saw that 'Urwa bin Az-Zubair had offered two rak`at in the Maghrib prayer and finished it with Taslim. He then talked (and when he was informed about it) he completed the rest of his prayer and performed two prostrations, and said, 'The Prophet prayed like this.'

Narrated Abu Huraira.: Once Allah's Apostle offered two rak`at and finished his prayer. So Dhul-Yadain asked him, Has the prayer been reduced or have you forgotten? Allah's Apostle said, Has Dhul-Yadain spoken the truth? The people replied in the affirmative. Then Allah's Apostle stood up and offered the remaining two rak`at and performed Taslim, and then said Takbir and performed two prostrations like his usual prostrations, or a bit longer, and then got up.

Narrated Abu Huraira: The Prophet offered one of the evening prayers (the sub-narrator Muhammad said, I think that it was most probably the `Asr prayer ) and he finished it after offering two rak`at only. He then stood near a price of wood in front of the Mosque and put his hand over it. Abu Bakr and `Umar were amongst those who were present, but they dared not talk to him about that (because of excessive respect for him), and those who were in a hurry went out. They said, Has the prayer been reduced? A man who was called Dhul-Yadain by the Prophet said (to the Prophet), Has the prayer been reduced or have you forgotten? He said, Neither have I forgotten, nor has the prayer been reduced. He said, Certainly you have forgotten. So the Prophet offered two more rak`at and performed Taslim and then said Takbir and performed a prostration of Sahu like his ordinary prostration or a bit longer and then raised his head and said Takbir and then put his head down and performed a prostration like his ordinary prostration or a bit longer, and then raised his head and said Takbir.

Narrated `Abdullah bin Buhaina Al-Asdi: (the ally of Bani `Abdul Muttalib) Allah's Apostle stood up for the Zuhr prayer and he should have sat (after the second rak`a but he stood up for the third rak`a without sitting for Tashah-hud) and when he finished the prayer he performed two prostrations and said Takbir on each prostration while sitting, before ending (the prayer) with Taslim; and the people too performed the two prostrations with him instead of the sitting he forgot.

Narrated Abu Huraira: Allah's Apostle said, When the call for prayer is made, Satan takes to his heels passing wind so that he may not hear the Adhan and when the call is finished he comes back, and when the Iqama is pronounced, Satan again takes to his heels, and when the Iqama is finished he comes back again and tries to interfere with the person and his thoughts and say, Remember this and that (which he has not thought of before the prayer) , till the praying person forgets how much he has prayed. If anyone of you does not remember whether he has offered three or four rak`at then he should perform two prostrations of Sahu while sitting.

Narrated Abu Huraira: Allah's Apostle said, When anyone of you stands for the prayers, Satan comes and puts him in doubts till he forgets how many rak`at he has prayed. So if this happens to anyone of you, he should perform two prostrations of Sahu while sitting.

Narrated Kuraib: I was sent to Aisha by Ibn `Abbas, Al-Miswar bin Makhrama and `Abdur-Rahman bin Azhar . They told me to greet her on their behalf and to ask her about the offering of the two rak`at after the `Asr prayer and to say to her, We were informed that you offer those two rak`at and we were told that the Prophet had forbidden offering them. Ibn `Abbas said, I along with `Umar bin Al-Khattab used to beat the people whenever they offered them. I went to Aisha and told her that message. `Aisha said, Go and ask Um Salama about them. So I returned and informed them about her statement. They then told me to go to Um Salama with the same question with which t sent me to `Aisha. Um Salama replied, I heard the Prophet forbidding them. Later I saw him offering them immediately after he prayed the `Asr prayer. He then entered my house at a time when some of the Ansari women from the tribe of Bani Haram were sitting with me, so I sent my slave girl to him having said to her, 'Stand beside him and tell him that Um Salama says to you, O Allah's Apostle! I have heard you forbidding the offering of these (two rak`at after the `Asr prayer) but I have seen you offering them. If he waves his hand then wait for him.' The slave girl did that. The Prophet beckoned her with his hand and she waited for him. When he had finished the prayer he said, O daughter of Bani Umaiya! You have asked me about the two rak`at after the `Asr prayer. The people of the tribe of `Abdul-Qais came to me and made me busy and I could not offer the two rak`at after the Zuhr prayer. These (two rak`at that I have just prayed) are for those (missed) ones.