Musannaf Ibn Abi Shaybah 4562 — What one does on forgetting

Qays said: Sayyiduna Sa'd bin Malik (may Allah be pleased with him) led his companions in prayer. He stood up in the third rak'ah, and the people said "Subhan Allah", but he did not sit; he too said "Subhan Allah" and gestured to the people to stand up. Then he led the prayer and performed the two prostrations of forgetfulness.