عَنْ ثَوْبَانَ رَضِيَ اللَّهُ عَنْهُ (مَوْلَى رَسُولِ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَآلِهِ وَسَلَّمَ) عَنِ النَّبِيِّ صَلَّى اللَّهُ عَلَيْهِ وَآلِهِ وَسَلَّمَ أَنَّهُ قَالَ: ((لِكُلِّ سَهْوٍ سَجْدَتَانِ بَعْدَ مَا يُسَلِّمُ))
Mawla of the Messenger, Sayyiduna Thawban (may Allah be pleased with him) narrates that the Noble Prophet (peace and blessings be upon him and his family) said: For every forgetfulness, there are two prostrations after completing the prayer with salam.