The Messenger of Allah ﷺ said: When any one of you is in doubt about his prayer and he does Dot know how much he has prayed, three or four (rak'ahs). he should cast aside his doubt and base his prayer on what he is sure of. then perform two prostrations before giving salutations. If he has prayed five rak'ahs, they will make his prayer an even number for him, and if he has prayed exactly four, they will be humiliation for the devil.  

قَالَ رَسُولُ اللَّهِ ﷺ إِذَا شَكَّ أَحَدُكُمْ فِي صَلاَتِهِ فَلَمْ يَدْرِ كَمْ صَلَّى ثَلاَثًا أَمْ أَرْبَعًا فَلْيَطْرَحِ الشَّكَّ وَلْيَبْنِ عَلَى مَا اسْتَيْقَنَ ثُمَّ يَسْجُدُ سَجْدَتَيْنِ قَبْلَ أَنْ يُسَلِّمَ فَإِنْ كَانَ صَلَّى خَمْسًا شَفَعْنَ لَهُ صَلاَتَهُ وَإِنْ كَانَ صَلَّى إِتْمَامًا لأَرْبَعٍ كَانَتَا تَرْغِيمًا لِلشَّيْطَانِ  

The Prophet ﷺ said: "If one of you is not sure about his prayer, let him forget about what he is unsure of and complete his prayer on the basis of what he is sure of. When he is sure that he has completed it, let him prostrate twice while he is sitting. Then if he has prayed five (rak'ahs), they (the two prostrations) will make his prayer even-numbered, and if he had prayed four, they will annoy and humiliate the shaitan."  

عَنِ النَّبِيِّ ﷺ قَالَ إِذَا شَكَّ أَحَدُكُمْ فِي صَلاَتِهِ فَلْيُلْغِ الشَّكَّ وَلْيَبْنِ عَلَى الْيَقِينِ فَإِذَا اسْتَيْقَنَ بِالتَّمَامِ فَلْيَسْجُدْ سَجْدَتَيْنِ وَهُوَ قَاعِدٌ فَإِنْ كَانَ صَلَّى خَمْسًا شَفَعَتَا لَهُ صَلاَتَهُ وَإِنْ صَلَّى أَرْبَعًا كَانَتَا تَرْغِيمًا لِلشَّيْطَانِ  

The Prophet ﷺ said: "If one of you does not know whether he prayed three or four (rak'ahs), let him pray a rak'ah then prostrate twice after that when he is sitting. Then if he prayed five (rak'ahs), they (the two prostrations) will make his prayer even-numbered, and if he had prayed four, they will annoy and humiliate the shaitan."  

عَنِ النَّبِيِّ ﷺ قَالَ إِذَا لَمْ يَدْرِ أَحَدُكُمْ صَلَّى ثَلاَثًا أَمْ أَرْبَعًا فَلْيُصَلِّ رَكْعَةً ثُمَّ يَسْجُدْ بَعْدَ ذَلِكَ سَجْدَتَيْنِ وَهُوَ جَالِسٌ فَإِنْ كَانَ صَلَّى خَمْسًا شَفَعَتَا لَهُ صَلاَتَهُ وَإِنْ صَلَّى أَرْبَعًا كَانَتَا تَرْغِيمًا لِلشَّيْطَانِ  

The Prophet ﷺ said: When one of you is in doubt about his prayer, and does not know how much he has prayed, three or four rak'ahs, he should pray one (additional) rak'ah and make two prostrations while sitting before giving the salutation. If the (additional) rak'ah which he prayed is the fifth one, he will make it an even number by these two prostrations. If it is the fourth one, the two prostrations will be a disgrace for the devil.  

أَنَّ رَسُولَ اللَّهِ ﷺ قَالَ إِذَا شَكَّ أَحَدُكُمْ فِي صَلاَتِهِ فَلاَ يَدْرِي كَمْ صَلَّى ثَلاَثًا أَوْ أَرْبَعًا فَلْيُصَلِّ رَكْعَةً وَيَسْجُدْ سَجْدَتَيْنِ وَهُوَ جَالِسٌ قَبْلَ التَّسْلِيمِ فَإِنْ كَانَتِ الرَّكْعَةُ الَّتِي صَلَّى خَامِسَةً شَفَعَهَا بِهَاتَيْنِ وَإِنْ كَانَتْ رَابِعَةً فَالسَّجْدَتَانِ تَرْغِيمٌ لِلشَّيْطَانِ  

Yahya related to me from Malik from Zayd ibn Aslam from Ata ibn Yasar that the Messenger of Allah ﷺ said, "If you are uncertain in the prayer and do not know whether you have prayed three or four rakas, then pray a raka and make two prostrations from the sitting position before the taslim. If the raka that you prayed was the fifth, then you make it even by these two sajdas, and if it was the fourth, then the two prostrations spite Shaytan."  

أَنَّ رَسُولَ اللَّهِ ﷺ قَالَ إِذَا شَكَّ أَحَدُكُمْ فِي صَلاَتِهِ فَلَمْ يَدْرِ كَمْ صَلَّى أَثَلاَثًا أَمْ أَرْبَعًا فَلْيُصَلِّي رَكْعَةً وَلْيَسْجُدْ سَجْدَتَيْنِ وَهُوَ جَالِسٌ قَبْلَ التَّسْلِيمِ فَإِنْ كَانَتِ الرَّكْعَةُ الَّتِي صَلَّى خَامِسَةً شَفَعَهَا بِهَاتَيْنِ السَّجْدَتَيْنِ وَإِنْ كَانَتْ رَابِعَةً فَالسَّجْدَتَانِ تَرْغِيمٌ لِلشَّيْطَانِ  

[Machine] The Messenger of Allah ﷺ said: "If anyone of you has doubt in their prayer and does not know whether they prayed three or four [rak'ahs], they should disregard their doubt and proceed according to what they are certain about. Then they should perform two prostrations before concluding their Salah. Because if they prayed five [rak'ahs], it will make up for their prayer as a whole." Musa said once, "If they prayed five [rak'ahs], they would make up for their prayer. And if they completed four [rak'ahs], they would prevent Satan from harm."  

قَالَ رَسُولُ اللهِ ﷺ إِذَا شَكَّ أَحَدُكُمْ فِي صَلَاتِهِ فَلَمْ يَدْرِ كَمْ صَلَّى ثَلَاثًا أَمْ أَرْبَعًا فَلْيَطْرَحِ الشَّكَّ وَلْيَبْنِ عَلَى مَا اسْتَيْقَنَ ثُمَّ يَسْجُدْ سَجْدَتَيْنِ قَبْلَ أَنْ يُسَلِّمَفَإِنْ كَانَ صَلَّى خَمْسًا كَانَتْ شَفْعًا لِصَلَاتِهِ قَالَ مُوسَى مَرَّةً فَإِنْ كَانَ صَلَّى خَمْسًا شَفَعْنَ لَهُ صَلَاتَهُ وَإِنْ كَانَ صَلَّى إِتْمَامَ أَرْبَعٍ كَانَتَا تَرْغِيمًا لِلشَّيْطَانِ  

[Machine] On the authority of the Prophet ﷺ, he said: If one of you has doubt during prayer and does not know whether they have prayed three or four (units), then they should get up and perform one unit of prayer (rakah). He said: Increase (the number of units of prayer) until the doubt is in the increase. Then, they should prostrate for the two prostrations of forgetfulness. If they prayed five (units of prayer), it will make up for their prayer. And if they prayed four, they will be compelled by the Satan.  

عَنِ النَّبِيِّ ﷺ قَالَ إِذَا شَكَّ أَحَدُكُمْ فِي الصَّلَاةِ فَلَمْ يَدْرِ ثَلَاثًا صَلَّى أَمْ أَرْبَعًا فَلْيَقُمْ فَلْيُصَلِّ رَكْعَةً قَالَ يَزِيدُ حَتَّى يَكُونَ الشَّكُّ فِي الزِّيَادَةِ ثُمَّ لِيَسْجُدْ سَجْدَتَيِ السَّهْوِ فَإِنْ كَانَ صَلَّى خَمْسًا شَفَعَتَا لَهُ صَلَاتَهُ وَإِنْ كَانَ صَلَّى أَرْبَعًا فَهُمَا يُرْغِمَانِ الشَّيْطَانَ  

The Prophet ﷺ said: "If one of you does not know whether he prayed three or four (rak'ahs), let him pray a rak'ah then prostrate twice after that when he is sitting. Then if he prayed five (rak'ahs), they (the two prostrations) will make his prayer even-numbered, and if he had prayed four, they will annoy and humiliate the shaitan." (Using translation from Nasāʾī 1239)   

قَالَ رَسُولُ اللَّهِ ﷺ «إِذَا لَمْ يَدْرِ أَحَدُكُمْ أَثَلَاثًا صَلَّى أَمْ أَرْبَعًا فَلْيَقُمْ فَلْيُصَلِّ رَكْعَةً ثُمَّ لِيَسْجُدْ بَعْدَ ذَلِكَ سَجْدَتَيْنِ فَإِنْ كَانَ صَلَّى خَمْسًا شَفَعَتَا لَهُ صَلَاتَهُ وَإِنْ كَانَ صَلَّى أَرْبَعًا كَانَتَا تَرْغِيمًا لِلشَّيْطَانِ» قَالَ أَبُو مُحَمَّد «آخُذُ بِهِ»  

[Machine] The Messenger of Allah ﷺ said, "If one of you is unsure whether he has prayed three or four (rak'ahs), then he should complete it and perform one more rak'ah, then make two prostrations of forgetfulness while sitting. If his prayer was five (rak'ahs), then the extra rak'ah is a voluntary prayer, and if it was four (rak'ahs), then they are a means of thwarting Satan, and this is their meaning."  

قَالَ رَسُولُ اللهِ ﷺ إِذَا لَمْ يَدْرِ أَحَدُكُمْ ثَلَاثًا صَلَّى أَمْ أَرْبَعًا؟ فَلْيُتِمَّ وَيُصَلِّي رَكْعَةً ثُمَّ يَسْجُدْ بَعْدَ ذَلِكَ سَجْدَتَيِ السَّهْوِ وَهُوَ جَالِسٌ فَإِنْ كَانَتْ صَلَاتُهُ خَمْسًا شَفَعَتْ صَلَاتَهُ وَإِنْ كَانَتْ أَرْبَعًا كَانَتَا تَرْغِيمًا لِلشَّيْطَانِ وَبِمَعْنَاهُ  

"إِذا صلَّى أحدُكُمْ فلم يدرِ ثلاثًا صلى أم أربعًا؟ فْلُيصلِّ ركعةً ويسجُدْ سجدتين قَبل السلام، فإنْ كانَتْ ثالثةً شفعها السَّجدتان، وإنْ كانَتْ رابعةً فالسجدتان تَرْغيمٌ للشَّيطْان".  

The Messenger of Allah ﷺ said: When any one of you is in doubt about his prayer and he does Dot know how much he has prayed, three or four (rak'ahs). he should cast aside his doubt and base his prayer on what he is sure of. then perform two prostrations before giving salutations. If he has prayed five rak'ahs, they will make his prayer an even number for him, and if he has prayed exactly four, they will be humiliation for the devil. (Using translation from Muslim 571a)   

"إذا شكَّ أحدُكُمْ في صلاتِه فلمْ يَدْرِ كم صلَّى، ثلاثًا أمْ أربْعًا؟ فليَطرحْ الشَّكَ ولْيبْنِ على ما اسْتيقَنَ ثُمَّ يَسْجُدْ سجْدَتين قْبلَ أنْ يُسلِّمَ، فإِن كانَ صلَّى خمسًا شَفعْن له صَلاته، وإنْ كانَ صلَّى إتْمامًا لأربعٍ كانتا تَرْغيما للشَّيطان".