Abdullah bin Masud reported,

The Messenger of Allah ﷺ led us in prayer and either added to it or left something out. When he gave the closing salam, we said, "Prophet of Allah, has something changed in the prayer?"He asked, "What do you mean?"We told him what he had done. So he turned his leg, faced the qiblah, and performed the two prostrations of forgetfulness. Then he turned his face toward us and said, "If anything had changed in the prayer, I would have informed you of it." Then he said, "I am only a human being. I forget just as you forget. So whichever of you has any doubt in his prayer, let him strive to determine what he believes is correct, then complete the prayer with the salam, and then perform the two prostrations of forgetfulness."

أخبرنا الحسن بن إسمعيل بن سليمان المجالدي قال حدثنا الفضيل يعني ابن عياض عن منصور عن إبراهيم عن علقمة

عن عبد الله قال

صلى رسول الله ﷺ صلاة فزاد فيها أو نقص فلما سلم قلنا يا نبي الله هل حدث في الصلاة شيء قال وما ذاك فذكرنا له الذي فعل فثنى رجله فاستقبل القبلة فسجد سجدتي السهو ثم أقبل علينا بوجهه فقال لو حدث في الصلاة شيء لأنبأتكم به ثم قال إنما أنا بشر أنسى كما تنسون فأيكم شك في صلاته شيئا فليتحر الذي يرى أنه صواب ثم يسلم ثم يسجد سجدتي السهو