The ruling on following the imam in an extra rak'ah
Machine translationRead the Arabic original
Question:
If the imam prays a fifth rak'ah and the ma'mum has missed a rak'ah. Yes.
Answer:
He does not say the taslim with him; he stands and recites one al-Fatihah and does not follow him. If he knows that it is an extra rak'ah, he does not follow him. If he follows him while ignorant, that rak'ah does not count; it is treated as if it did not exist. It is ruled as non-existent because his making up the prayer occurs after the taslim and the turban.
If the imam prays a fifth rak'ah and the ma'mum has missed a rak'ah. Yes.
Answer:
He does not say the taslim with him; he stands and recites one al-Fatihah and does not follow him. If he knows that it is an extra rak'ah, he does not follow him. If he follows him while ignorant, that rak'ah does not count; it is treated as if it did not exist. It is ruled as non-existent because his making up the prayer occurs after the taslim and the turban.
Source
شرح بلوغ المرام [ ابن باز ] [ الشرح الجديد ]، تتمة أحاديث في الجنايات — islamhouse.com (0:38)
The Arabic text is a machine transcription of the audio recording.