It is recommended for pilgrims and others to enter the Ka'bah and pray therein, and supplicate in all its corners Sahih Muslim 1332
Arabic hadith text
وَحَدَّثَنِي سُرَيْجُ بْنُ يُونُسَ، حَدَّثَنِي هُشَيْمٌ، أَخْبَرَنَا إِسْمَاعِيلُ بْنُ أَبِي خَالِدٍ، قَالَ قُلْتُ لِعَبْدِ اللَّهِ بْنِ أَبِي أَوْفَى صَاحِبِ رَسُولِ اللَّهِ صلى الله عليه وسلمأَدَخَلَ النَّبِيُّ صلى الله عليه وسلم الْبَيْتَ فِي عُمْرَتِهِ قَالَ لاَ
Translation
Isma'il b. Abu Khalid reported
I asked Abdullah b. Abu Aufa (Allah be pleased with him), a Companion of Allah's Messenger (ﷺ), whether Allah's Apostle (ﷺ) had entered the House, while performing 'Umra, He said: NO.