HIJR OR BABUL HIJR
Babul Hijr is a door or place between Hateem and the wall of Kaba.
The Prophet ﷺ circumambulated the House from outside the Hijr. If a person circumambulates the Ka’bah going inside the Hijr, he is not regarded as having circumambulated the House, so his tawaaf is invalid. This is a serious matter, especially since tawaaf is a pillar (essential part) of both Hajj and ‘Umrah.
many people call the Hijr “Hijr Ismaa’eel”, but in fact Ismaa’eel(Peace be upom him) had nothing to do with it and it is not his Hijr. Rather this Hijr came into being when Quraysh ran short of cash, when they wanted to rebuild the Ka’bah, and they did not have enough resources to build the Ka’bah on the foundations of Ibraaheem, so they left this side out of it, and it was called hateem and hijr; so Ismaa’eel knew nothing of it and had nothing to do with it.
Shaykh Muhammad ibn ‘Uthaymeen (may Allaah have mercy on him) said:
This is a very serious mistake, when some people enter through the gate of the Hijr when doing Tawaf and exit through the other gate when it is crowded, thinking that this is easier. It is a serious mistake because the one who does that is not considered to be doing tawaaf around the Ka’bah. Allaah says (interpretation of the meaning): “and circumambulate the Ancient House (the Ka‘bah at Makkah)”Quran Surah al-Hajj 22:29