When you offer the prayer, and you are in doubt about the number of rak'ahs whether offered three or four, and you have prayed four rak'ahs in all probability in your opinion, you should recite tashahhud and make two prostrations while you are sitting before giving the salutation. afterwards you should recite the tashahhud and give the salutation again. Abu Dawud said: This tradition has been narrated by 'Abd al-Wahid from Khusaif, but he did not report it as a statement of the Prophet ﷺ. The version of 'Abd al-Wahid has been corroborated by Sufyan, Sharik, and Isra'il. They differed amongst themselves about the text of the tradition and they did not narrate it with the continuous chain up to the Prophet ﷺ.  

عَنْ رَسُولِ اللَّهِ ﷺ قَالَ إِذَا كُنْتَ فِي صَلاَةٍ فَشَكَكْتَ فِي ثَلاَثٍ أَوْ أَرْبَعٍ وَأَكْبَرُ ظَنِّكَ عَلَى أَرْبَعٍ تَشَهَّدْتَ ثُمَّ سَجَدْتَ سَجْدَتَيْنِ وَأَنْتَ جَالِسٌ قَبْلَ أَنْ تُسَلِّمَ ثُمَّ تَشَهَّدْتَ أَيْضًا ثُمَّ تُسَلِّمُ  

The Prophet ﷺ said: When one of you prays, and he does not know whether he prayed more or less rak'ahs (than those prescribed by the Shari'ah), he should perform two prostrations while he is sitting. If the devil comes to him, and tells him (suggests him): "You have been defiled," he should say: "You have told a lie," except that he feels smell with his nose, or sound with his ears (then his ablution will break). These are the wording; of the tradition reported by Aban. Abu Dawud said: Ma'mar and 'Abi b. al-Mubarak mentioned the name "Iyad b. Hilal and al-Awza'i mentioned the name of Iyad b. Abi Zuhair.  

أَنَّ رَسُولَ اللَّهِ ﷺ قَالَ إِذَا صَلَّى أَحَدُكُمْ فَلَمْ يَدْرِ زَادَ أَمْ نَقَصَ فَلْيَسْجُدْ سَجْدَتَيْنِ وَهُوَ قَاعِدٌ فَإِذَا أَتَاهُ الشَّيْطَانُ فَقَالَ إِنَّكَ قَدْ أَحْدَثْتَ فَلْيَقُلْ كَذَبْتَ إِلاَّ مَا وَجَدَ رِيحًا بِأَنْفِهِ أَوْ صَوْتًا بِأُذُنِهِ وَهَذَا لَفْظُ حَدِيثِ أَبَانَ  

Abu Hurairah reported the Messenger of Allah ﷺ as saying; When one of you stands up to pray, the devil comes to him and confuses him so that he does not know how much he has prayed. If any of you has such an experience, he should perform two prostrations while he is sitting. Abu Dawud said; This tradition has been narrated in a similar manner by Ibn ‘Uyainab, Ma’mar and al-Laith.  

أَنَّ رَسُولَ اللَّهِ ﷺ قَالَ إِنَّ أَحَدَكُمْ إِذَا قَامَ يُصَلِّي جَاءَهُ الشَّيْطَانُ فَلَبَسَ عَلَيْهِ حَتَّى لاَ يَدْرِي كَمْ صَلَّى فَإِذَا وَجَدَ أَحَدُكُمْ ذَلِكَ فَلْيَسْجُدْ سَجْدَتَيْنِ وَهُوَ جَالِسٌ  

This tradition has also been transmitted by Muhammad b. Muslim through a different chain of narrators. This version adds; “While he is sitting before he gives the salutation.”  

عَنْ مُحَمَّدِ بْنِ مُسْلِمٍ بِهَذَا الْحَدِيثِ بِإِسْنَادِهِ زَادَ وَهُوَ جَالِسٌ قَبْلَ التَّسْلِيمِ  

This traditions has also been narrated by Muhammad b. Muslim al-Zuhr through a different chain of transmitters and to the same effect. This version adds; He should perform two prostrations before giving the salutation.  

أَنْ يُسَلِّمَ ثُمَّ لْيُسَلِّمْ