1088 - Al-Musayyab ibn Wadih narrated to us, he said: I asked Abu Ishaq al-Fazari about a man who left out both Tashahhud recitations? He said: "His prayer is valid."
Chapter: Regarding the one who missed part of the prayer with the Imam, and recites the Tashahhud repeatedly.
• I heard Ahmad say - regarding a man who missed part of the prayer with the Imam -; he said: "If he sits with the Imam at the end of his [the Imam's] prayer, he should repeat the Tashahhud and not make supplication (Du'a)."
• Ahmad was asked - another time - about the man who arrives while the Imam is sitting, so he says the Takbir and sits; should he recite the Tashahhud? If the Imam prolongs the sitting, he should repeat the Tashahhud (1). It was said: What if he finishes the Tashahhud and the Imam prolongs it, should he remember Allah? He said: "It is more beloved to me that he recites the Tashahhud, and when he stands up, he says the Takbir."
• I asked Ishaq, I said: A man missed part of the prayer with the Imam, and when he sat with the Imam at the end of his prayer, the Imam prolonged the Tashahhud, and this [person] had not yet completed his prayer? Abu Ya'qub said: "He should repeat the Tashahhud," meaning: he should not make supplication except at the end of his own prayer.
1089 - Abu Hafs narrated to us, he said: Bishr ibn al-Waddah narrated to us, he said: Mubarak narrated to us, from al-Hasan - regarding the man who is late for part of the prayer and sits with the Imam at the end of the prayer -; he said: "He should repeat the Tashahhud and not make supplication."
(1) Thus it is in the original, and it is possible that something was omitted from it, and it is likely that the correct wording is: "He said: If he prolongs..."