Fiqh-us-Sunnah Volume 5, Hajj and ‘Umrah, Fiqh 5.123.

Section : Miqat for ‘Umrah.

In case a person intending to perform ‘Umrah is outside the miqat fixed for Hajj, it is not permitted for him to cross these miqats (places fixed for ihram) without declaring ihram.

Bukhari has reported that Zaid bin Jubair came to Ibn ‘Umar and asked him, “Wherefrom should I declare my intention to perform ‘Umrah?” He replied, “The Prophet (peace be upon him) has set Qarna as the miqat for the people of Najd (from where they must declare their ihram), and similarly for the people of Madinah he set Zhul Hulaifah, and for the people of Syria AlJohfah as their miqats.”

One who is already well within the confines of the miqat area – even if one is within the Sacred Precincts of Haram itself – must go out to the miqat and declare ihram from there, as is obvious from the above hadith of Bukhari which says that ‘Aishah was commanded by the Prophet (peace be upon him) to go to Tan’im (the miqat) and put on her ihram for ‘Umrah from there.