"I said to Abu Sa'eed: 'One of us performs Salat and we do not know how (much) we prayed.' So he said: 'Messenger of Allah (S) said: "When one of you performs Salat and he does now know how (much) he prayed then let him perform two prostrations while he is sitting."  

قُلْتُ لأَبِي سَعِيدٍ أَحَدُنَا يُصَلِّي فَلاَ يَدْرِي كَيْفَ صَلَّى فَقَالَ قَالَ رَسُولُ اللَّهِ ﷺ إِذَا صَلَّى أَحَدُكُمْ فَلَمْ يَدْرِ كَيْفَ صَلَّى فَلْيَسْجُدْ سَجْدَتَيْنِ وَهُوَ جَالِسٌ قَالَ وَفِي الْبَابِ عَنْ عُثْمَانَ وَابْنِ مَسْعُودٍ وَعَائِشَةَ وَأَبِي هُرَيْرَةَ  

“One of us prays and he does not know how many (Rak’ah) he has prayed.” He said: “The Messenger of Allah ﷺ said: ‘When anyone of you prays and does not know how many he has prayed, let him perform two prostrations while he is sitting.’” (Using translation from Ibn Mājah 1204)   

سَأَلْتُ أَبَا سَعِيدٍ الْخُدْرِيِّ قُلْتُ يُصَلِّي أَحَدُنَا فَلَا يَدْرِي كَمْ صَلَّى؟ قَالَ قَالَ رَسُولُ اللهِ ﷺ «إِذَا صَلَّى أَحَدُكُمْ فَلَمْ يَدْرِ كَمْ صَلَّى فَلْيَسْجُدْ سَجْدَتَيْنِ وَهُوَ جَالِسٌ»  

[Machine] The Messenger of Allah ﷺ said, "If one of you prays and forgets or does not know if they have added or missed something, they should perform two prostrations while sitting."  

قَالَ رَسُولُ اللهِ ﷺ «إِذَا صَلَّى أَحَدُكُمْ فَنَسِيَ» أَوْ قَالَ «فَلَمْ يَدْرِ زَادَ أَوْ نَقَصَ فَلْيَسْجُدْ سَجْدَتَيْنِ وَهُوَ جَالِسٌ»  

[Machine] The Messenger of Allah ﷺ said, "If one of you prays and does not know if he has added or subtracted, he should perform two prostrations while sitting and then say the salaam."  

قَالَ رَسُولُ اللهِ ﷺ «إِذَا صَلَّى أَحَدُكُمْ فَلَا يَدْرِي أَزَادَ أَوْ نَقَصَ فَلْيَسْجُدْ سَجْدَتَيْنِ وَهُوَ جَالِسٌ ثُمَّ يُسَلِّمُ»  

"إذَا صَلَّى أحدُكم فلمْ يدْرِ كيف صلَّى؟ فليسجدْ سجدَتين وَهُوَ جَالِسٌ".