Hazrat Anas and Hasan say that he will act upon his last doubt and perform Sajdah Sahw.

Hazrat Ibn Umar (may Allah be pleased with them) said: Count as much as you are able, and do not repeat the prayer.

Hazrat Abdul Aziz bin Suhaib says that Hazrat Anas bin Malik (may Allah be pleased with him) sat for Tashahhud in the third rak'ah, so the people behind him said tasbih. He stood up and completed the fourth rak'ah. When he finished with salam, he performed two prostrations of forgetfulness (sujood as-sahw). Then, turning towards the people, he said: "When you are in doubt, do like this."

It is narrated from Hazrat Abu Huraira that the Messenger of Allah, peace and blessings be upon him, said: When you forget the amount of prayer, then while sitting in the position of Tashahhud, perform two prostrations of forgetfulness (sujood as-sahw).

Hazrat Ibn Umar (may Allah be pleased with them both) said: If I do not know how many units of prayer I have performed, I will repeat the prayer.

Hazrat Ibn Umar (may Allah be pleased with them both), regarding the person who does not remember whether he has prayed three rak‘ahs or four, says that he should repeat the prayer so that he may remember.

Hazrat Sha'bi and Hazrat Sa'id bin Jubair state that if a person finishes the prayer and does not know whether he has prayed an odd or even number of units, then he should repeat the prayer.

4488 - (W) (1) From Ayyub, from Sa'id ibn Jubayr, they said: If he prays and then leaves but does not know how many (rak'ahs) he prayed, whether even or odd, then let him repeat it.

It is narrated similarly through another chain.

Hazrat Mansur says that I asked Hazrat Saeed bin Jubair about a person who has doubt in prayer. He said, if this happens to me in obligatory prayer, I will repeat the prayer.