أَنَّهُ دَخَلَ الْبَيْتَ وَصَلَّى فِيهِ.
Translation: He entered the House and prayed inside it.
The narration reported from Bilal concerning the Prophet’s prayer inside the Kaaba supports the underlying permissibility of prayer there.
Whether that permissibility includes obligatory prayer is a further juristic question; it should not be treated as identical to the authenticity of the incident.