It is narrated from Sayyiduna Muawiyah (may Allah be pleased with him) that once he led the prayer as an imam and instead of sitting, he stood up. The people also said «سبحان اللہ», but he completed his standing. Then after completing the prayer, while sitting, he performed two prostrations of forgetfulness, and after ascending the pulpit, he said: I heard the Prophet (peace and blessings of Allah be upon him) say that if a person forgets something in prayer, he should perform two prostrations in this manner while sitting.