Sunan an-Nasa'i, Volume 3, Book 24, Hadith 2910 (DarusSalam) ⓘ

It was narrated that Ibn Umar said: "The Messenger of Allah entered the Kabah, and was about to come out, when I thought of something, so I came quickly and I found the Messenger of Allah coming out. I asked Bilal: Did the Messenger of Allah prayed inside the Kabah?' He said: 'Yes, two Rakahs between the two columns.'"

أَخْبَرَنَا عَمْرُو بْنُ عَلِيٍّ، قَالَ حَدَّثَنَا يَحْيَى، قَالَ حَدَّثَنَا السَّائِبُ بْنُ عُمَرَ، قَالَ حَدَّثَنِي ابْنُ أَبِي مُلَيْكَةَ، أَنَّ ابْنَ عُمَرَ، قَالَ دَخَلَ رَسُولُ اللَّهِ صلى الله عليه وسلم الْكَعْبَةَ وَدَنَا خُرُوجُهُ وَوَجَدْتُ شَيْئًا فَذَهَبْتُ وَجِئْتُ سَرِيعًا فَوَجَدْتُ رَسُولَ اللَّهِ صلى الله عليه وسلم خَارِجًا فَسَأَلْتُ بِلاَلاً أَصَلَّى رَسُولُ اللَّهِ صلى الله عليه وسلم فِي الْكَعْبَةِ قَالَ نَعَمْ رَكْعَتَيْنِ بَيْنَ السَّارِيَتَيْنِ ‏.‏