If a pillar is left out in the second rak'ah and one remembers after finishing the prayer, what does he do?
Machine translationRead the Arabic original
The questioner : He left out a pillar in the second rak'ah.
The Shaykh : If what?
The questioner : He left out a pillar from the rak'ah. Yes. And he testifies a second time?
The Shaykh : The second movement.
The questioner : Yes.
The Shaykh : Now that he has finished the prayer and remembered that he left out a pillar in the second rak'ah, we say that the third rak'ah took the place of the second, and the fourth took the place of the third. So he now comes with a fourth rak'ah, testifies, says the closing salam, and performs the prostration for forgetfulness after the salam.
The Shaykh : If what?
The questioner : He left out a pillar from the rak'ah. Yes. And he testifies a second time?
The Shaykh : The second movement.
The questioner : Yes.
The Shaykh : Now that he has finished the prayer and remembered that he left out a pillar in the second rak'ah, we say that the third rak'ah took the place of the second, and the fourth took the place of the third. So he now comes with a fourth rak'ah, testifies, says the closing salam, and performs the prostration for forgetfulness after the salam.
Source
قناة «فضيلة الشيخ محمد بن صالح العثيمين»، 1115 - إذا ترك ركن في الركعة الثانية وتذكر بعد انتهائه من الصلاة ماذا يفعل؟ ابن عثيمين — youtube.com
The Arabic text is a machine transcription of the audio recording.