Narrated by Muhammad ibn Ahmad ibn Yahya, from Ali ibn Isma'il, from a man, from Mu‘alla ibn Khunays: I asked Abul Hasan al-Madi عليه السلام about a man who forgets a prostration in his prayer. Imam عليه السلام said: "If he remembers it before his bowing, he should perform it and continue with his prayer, then perform the two prostrations of forgetfulness (sajdatay al-sahw) after completing the prayer. But if he remembers it after his bowing, he must repeat the prayer. Forgetting a prostration in the first two rak‘ahs and the last two rak‘ahs is the same."