Missing a rakah or adding a rakah

when one mistakenly misses or adds a rakat during prayer, it is part of forgetfulness, prostrations of sahu are not most commonly done before taslim, it can be before or after, but anyone is sufficient. 1.398: Narrated Abdullah: "Once the Prophet offered five rakat in Zuhr prayer. He was asked, "Is there an increase in the prayer?" The Prophet said, "And what is it?" They said, "You have prayed five rak`at.' So he bent his legs and performed two prostrations (of Sahu). Sahih Bukhari There are so many Hadiths in Sahih Bukhari that talks about Salat but i believe this should be sufficient. Wallahu alam

Wa alaikum salam wa Rahmatullah wa barakatu, if u feel you mistakenly add a rakat, u will perform the prostration of sahu after teslim, (this is prostrating twice after teslim) and then u make teslim again after the two prostrations. if u feel u mistakenly missed a rakat, u pray one more rakat to make up for the one u missed and then u perform the prostration of sahu after teslim. if u have left the mosque before u remember that u missed a rakat, u have to perform the prayer all over. if u have left the mosque before remembering that u added a rakat, u just perform the prostration of sahu and make teslim. wallahu alam

i understand what u said Al Ummat, but the prostration is meant for every kind of forgetfulness during prayer, whether missing or adding a rakat as clearly stated in this Hadith also 1.469: Narrates Ibn Seereen: Abu Huraira said, "Allah's Apostle led us in one of the two Isha' prayers (Abu Huraira named that prayer but I forgot it)." Abu Huraira added, "He prayed two rakat and then finished the prayer with Taslim. He stood up near a piece of wood Lying across the mosque and leaned on it in such a way as if he was angry. Then he put his right hand over the left and clasped his hands by interlacing his fingers and then put his J right cheek on the back of his left hand. The people who were in haste left the mosque through its gates. They wondered whether the prayer was reduced. And amongst them were Abu Bakr and Umar but they hesitated to ask the Prophet. A long−handed man called Dhul−Yadain asked the Prophet, 'O Allah's Apostle! Have you forgotten or has the prayer been reduced?' The Prophet replied, 'I have neither forgotten nor has the prayer been reduced' The Prophet added, 'Is what Dhul Yadain has said true?' They (the people) said, 'Yes, it is true.' The Prophet stood up again and led the prayer, completing the remaining prayer, forgotten by him, and performed Taslim, and then said, 'Allahu Akbar.' And then he did a prostration as he used to prostrate or longer than that. He then raised his head saying, 'Allahu Akbar; he then again said, 'Allahu Akbar', and prostrated as he used to prostrate or longer than that. Then he raised his head and said, 'Allahu Akbar.' " (The sub−narrator added, "I think that they asked (Ibn Seereen) whether the Prophet completed the prayer with Taslim. He replied, "I heard thatImran bin Husain had said, 'Then he (the Prophet) did Taslim."). Sahih bukhari

Beside sujud al sahw, in the condition of missing rakah, you must pray this rakah whenever you remember during your prayer. If you add rakah then do sujud al sahw only.