Sahih Muslim 1329 g
Salim b. Abdullah reported his father (Allah be pleased with him) saying:
I saw Allah's Messenger (ﷺ) entering the Ka'ba, and Usama b. Zaid, Bilal and 'Uthman b. Talha were along with him, but none (else) entered therein along with them. Then the door was closed for them from within. 'Abdullah b. Umar (Allah be pleased with them) said: Bilal and Uthman b. Talha informed me that Allah's Messenger (ﷺ) observed prayer in the interior of the Ka'ba between the two Yemenite pillars.
وَحَدَّثَنِي حَرْمَلَةُ بْنُ يَحْيَى، أَخْبَرَنَا ابْنُ وَهْبٍ، أَخْبَرَنِي يُونُسُ، عَنِ ابْنِ شِهَابٍ، أَخْبَرَنِي سَالِمُ بْنُ عَبْدِ اللَّهِ، عَنْ أَبِيهِ، قَالَ رَأَيْتُ رَسُولَ اللَّهِ صلى الله عليه وسلم دَخَلَ الْكَعْبَةَ هُوَ وَأُسَامَةُ بْنُ زَيْدٍ وَبِلاَلٌ وَعُثْمَانُ بْنُ طَلْحَةَ وَلَمْ يَدْخُلْهَا مَعَهُمْ أَحَدٌ ثُمَّ أُغْلِقَتْ عَلَيْهِمْ ‏.‏ قَالَ عَبْدُ اللَّهِ بْنُ عُمَرَ فَأَخْبَرَنِي بِلاَلٌ أَوْ عُثْمَانُ بْنُ طَلْحَةَ أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم صَلَّى فِي جَوْفِ الْكَعْبَةِ بَيْنَ الْعَمُودَيْنِ الْيَمَانِيَيْنِ.‏