It is narrated from Hazrat Abu Huraira (may Allah be pleased with him) that the Noble Prophet (peace and blessings be upon him) led them in prayer. During the prayer, the Noble Prophet (peace and blessings be upon him) made a mistake (of forgetfulness). So after saying the salam, he made two prostrations and then said the salam again.
Hadith Referenceمسند احمد / مسند المكثرين من الصحابة / 9777