Yahya related to me from Malik from Nafi that Abdullah ibn Umar, when questioned about forgetfulness in the prayer, said, "If you think that you have forgotten part of the prayer, then pray it."
Muwatta Malik Book 3, Hadith 69
← Previous Hadith Yahya related to me from Malik from Afif ibn Amr as-Sahmi that Ata ibn Yasar said, "I asked Abdullah ibn Amr ibn al-As and Kab al Ahbar about someone who was uncertain in his prayer, and did not know whether he had prayed three or four rakas. Both of them said, 'He should pray another raka and then do two sajdas from the sitting position.' "

Muwatta Malik Book 3, Hadith 68 Next Hadith → Yahya related to me from Malik from Ibn Shihab from al-Araj that Abdullah ibn Buhayna said, "The Messenger of Allah, may Allah bless him and grant him peace, prayed two rakas with us and then stood without sitting and the people stood with him. When he had finished the prayerand we had seen him say the taslim, he said 'Allah is greater' and did two sajdas from the sitting position and then said the taslim again."

Muwatta Malik Book 3, Hadith 70