The distance for that

Narrated Abdullah bin Umar:

It was narrated from Abdullah bin Umar that the Messenger of Allah ﷺ entered the Ka'bah with Usamah bin Zaid, Bilal and Uthman bin Talha al Hajabi, and locked the door behind him. Abdullah bin Umar said: "I asked Bilal when he came out: " What did the Messenger of Allah ﷺ do?" He said: "He stood with one pillar to his left, two pillars to his right and three pillars behind him - at that time the House stood on six pillars - and he prayed with approximately three forearm's length between him and the wall."

أَخْبَرَنَا مُحَمَّدُ بْنُ سَلَمَةَ، وَالْحَارِثُ بْنُ مِسْكِينٍ، قِرَاءَةً عَلَيْهِ وَأَنَا أَسْمَعُ، عَنِ ابْنِ الْقَاسِمِ، قَالَ حَدَّثَنِي مَالِكٌ، عَنْ نَافِعٍ، عَنْ عَبْدِ اللَّهِ بْنِ عُمَرَ، أَنَّ رَسُولَ اللَّهِ ﷺ دَخَلَ الْكَعْبَةَ هُوَ وَأُسَامَةُ بْنُ زَيْدٍ وَبِلاَلٌ وَعُثْمَانُ بْنُ طَلْحَةَ الْحَجَبِيُّ فَأَغْلَقَهَا عَلَيْهِ قَالَ عَبْدُ اللَّهِ بْنُ عُمَرَ فَسَأَلْتُ بِلاَلاً حِينَ خَرَجَ مَاذَا صَنَعَ رَسُولُ اللَّهِ ﷺ قَالَ جَعَلَ عَمُودًا عَنْ يَسَارِهِ وَعَمُودَيْنِ عَنْ يَمِينِهِ وَثَلاَثَةَ أَعْمِدَةٍ وَرَاءَهُ - وَكَانَ الْبَيْتُ يَوْمَئِذٍ عَلَى سِتَّةِ أَعْمِدَةٍ - ثُمَّ صَلَّى وَجَعَلَ بَيْنَهُ وَبَيْنَ الْجِدَارِ نَحْوًا مِنْ ثَلاَثَةِ أَذْرُعٍ .