Praise be to Allah.
It is a good idea to quote the two hadeeth first, then explain how they may be reconciled:
It was narrated that Ibn ‘Abbaas (may Allaah be pleased with him) said: “The Messenger of Allaah (peace and blessings of Allaah be upon him) defined the meeqaat of the people of Madeenah as Dhu’l-Hulayfah; that of the people of Shaam (Syria) as al-Jahfah; that of the people of Najd as Qarn al-Manaazil; and that of the people of Yemen as Yalamlam. And he said: “And these meeqaats are for the people at those very places, and besides them for those who come thorough those places with the intention of performing Hajj and 'Umrah; and whoever is living within these boundaries can enter Ihram from the place he starts, and the people of Makkah can start from Makkah.” Narrated by al-Bukhaari and Muslim.
It was narrated that ‘Aa’ishah (may Allaah be pleased with her) said: “The Messenger of Allaah (peace and blessings of Allaah be upon him) stopped at al-Mahassab. He called ‘Abd al-Rahmaan ibn ‘Abi Bakr and said to him, ‘Take your sister out of the Haram (sanctuary) – according to another version: to al-Tan’eem – and let her enter ihraam for ‘umrah, then let her circumambulate the House, and I will wait for you both here.’” She said: “So we went out and I entered ihraam, then I circumambulated the House and did sa’ee between al-Safa and al-Marwah. Then we came to the Messenger of Allaah (peace and blessings of Allaah be upon him) at his camp in the middle of the night, and he said, ‘Have you finished?’ I said, ‘Yes.’ He gave his companions permission to move on, and he went out to the Ka’bah and circumambulated it before Fajr prayer, then he left for Madeenah.”
Narrated by al-Bukhaari and Muslim.
Based on this it may be said that the hadeeth of Ibn ‘Abbaas is general in application and means that the people of Makkah should enter ihraam from Makkah for either Hajj or ‘Umrah performed on its own or for Hajj and ‘Umrah together (qiraan); the hadeeth about ‘Aa’ishah going out of the sanctuary (the Haram) with her brother ‘Abd al-Rahmaan to enter ihraam was a specific command issued by the Prophet (peace and blessings of Allaah be upon him) to her alone. The well known principle according to the scholars is that if there seems to be a contradiction between a general ruling and a specific ruling, then the specific outweighs the general, which in this case is entering ihraam for ‘Umrah from al-Tan’eem, or some other place outside the Haram. So the phrase “and the people of Makkah from Makkah” means that the people of Makkah should enter ihraam for Hajj offered on its own or for Hajj and ‘Umrah offered together (qiraan) from Makkah, and they do not have to go outside the Haram or to one of the other meeqaats mentioned in the hadeeth, in order to enter ihraam from there.
In the case of ‘Umrah offered on its own, the one who wants to enter ihraam and is already in Makkah or within the boundaries of the Haram has to go outside the Haram – to al-Tan’eem or elsewhere – and enter ihraam from there. This was the view of the majority of scholars. Al-Muhibb al-Tabari said: I do not know of anyone who described Makkah as a meeqaat for ‘Umrah.
So the phrase in the hadeeth of Ibn ‘Abbaas (may Allaah be pleased with him) “the people of Makkah can start from Makkah” is interpreted as referring specifically to those who are performing Hajj combined with ‘Umrah (qiraan) or Hajj on its own, not those who are performing ‘Umrah on its own.
This is supported by the fact that the Prophet (peace and blessings of Allaah be upon him) was never given the choice between two things but he always chose the easier option, so long as it was not a sin. If entering ihraam for ‘Umrah from inside the Haram was permissible then he would have chosen that option for ‘Aa’ishah, because it would have been easier and less burdensome for him and for ‘Aa’ishah and her brother, and he would not have told her to go outside the Haram or to al-Tan’eem and enter ihraam from there. The fact that he did not choose the option of entering ihraam from inside the Haram, which would have been easier for everyone concerned, and he chose the option of entering ihraam from outside the Haram, which is more difficult, indicates that one should enter ihraam for ‘Umrah from outside the Haram, and that this is a shar’i requirement for the one who wants to perform ‘Umrah on its own and is already in the Haram.
And Allaah is the Source of strength.
See al-Lajnah al-Daa’imah, 11/143.