Salim bin Abdullah narrates from his father (Sayyiduna Abdullah bin Umar, may Allah be pleased with them both), who narrates from Sayyiduna Umar (may Allah be pleased with him), that the Prophet Muhammad (peace and blessings be upon him) said: "Whoever is following the Imam (in prayer), it is not obligatory upon him to perform the prostration of forgetfulness (sajdah sahw) due to his own mistake. But if the Imam makes a mistake, then it is obligatory upon the Imam to perform sajdah sahw, and it is also obligatory upon those praying behind him. However, if someone praying behind the Imam makes a mistake, then sajdah sahw is not obligatory upon him; rather, the Imam suffices for him."