Many Ahadith indicate that the Hijr is part of the house, and is included in the verse:
"and circuabulate the Ancient House (the Ka'bah at Makkah)." (22:29)
Based on this, Tawaf must include going around the Hijr too;otherwise one's tawaf is not valid.
Al-Hijr is the place where Ibrahim (peace be upon him) left his wife Hajrah and son Ismail when he brought them to Makkah and told Hajrah (may peace be upon her) to build a small hut there. Quraysh included only part of Al-Hijr in the Ka'bah because the money they had prepared for building ran short.
When 'Abdullah bin Az-Zubair (Radhi Alaahu Anhu) took over Makkah, he knocked down the Kabah and rebuilt it including the Hijr. But Al-Hajjaj put it back as it was and built the wall on the foundations laid by Quraysh, and this is how it has remained till today, with part of the Hijr included in the kabah and part of it excluded.
Among the evidences of that, is the Hadith of Aishah (Radhi Alaahu Anha): "Were it not for the fact that your people are still so close to the time of Shirk or Jahiliyyah - I would have knocked down the Ka’bah, brought the door down to ground level, and made two doors for it, one on the east and one on the west (one through which the people could enter and another through which they could exit.), and I would have added six cubits of Hijr to it, for Qurayshreduced its area when they rebuit the Kabah" (Ahmed 6/204)
Ibn Umar (Radhi Alaahu Anha) said "Aishah heard this from Allah's Messenger (peace be upon him), and I think that the only reason why Allah's messenger (peace be upon him) did not
touch thetwo corners which are opposite the hijr is that the House was not built completely on the foundations laid by
Ibrahim." (Al-Bukhari 1583)
Many of the scholors mentioned that Ismail (peace be upon him) was buried in the Hijr beside the grave of his mother Hajrah (may peace be upon
her). But the reports that have been narrated concerning that are all Da'eef(weak) and none of them are Sahih. What indicates that they are not true is the fact that the senior Sahabah were present when Quraysh rebuilt the Ka'bah and they witnessed the digging of the foundations at that time , but not one of them reported that they saw any trace of a grave.
If that had been true,it would not have been permissible for us to step on the site of a grave, because the prophet forbade
us to walk or sit on the graves.
According to many Ahadith, the one who enters the Hijr is like one who enters the Ka'bah . It was reported that 'Aishah
narrated: " I wanted to enter the House and pray inside. Allah's Messenger (Peace be upon him) took me by the hand and led me inside the Hir and said: 'If you want to go inside the House then pray here, for it is part of the House, but your people reduced its area when they rebuilt it'" (Al-Nasai 2912)
It was reported by 'Abdul-Hameed bin jubair from his paternal aunt Safiyah bint Shaibah that Aishah (Radhi Alaahu Anha) asked the Prophet (Peace be upon him) : " O Messenger of Allah, can't I enter the House?" He said: "Enter Al-Hijr, for it is part of the House" (Al-Nasai 2911)
It was narrate in a sahih report that Ibn Abbas (Radhi Alaahu Anhu) said: "Pray in the place where the Chosen prayedand drink the drink of the righteous." It was said to Ibn Abbas (Radhi Alaahu Anhu): "What is the place where the Chosen prayed?" He said: "Beneath the downspout." He was asked, "What is the drink of the righteous?" He said: "The water of Zamzam" (Al-Azraqi1/318)
This points to the virtue of praying in Al-Hijr. With regard to the report from Al-'Ata, according to which he said, "Whoever stands beneath the downspout of the Kabah and calls upon Allah, his supplication will be answered and he will emerge free of sins as on the day his mother bore him, this is Daeef(weak) and cannot e used to prove anything. This is a matter of the unseen and cannot be traced with a sound chain of narrators going back to the Prophet or to any of the companions.