What is the ruling on someone from Mecca who performed Umrah and prayed the two rak'ahs in his house with the intention of Umrah, without going to the Miqat due to his ignorance?

The miqat for a Meccan seeking to perform 'Umrah is the nearest point outside the Sacred Precincts (al-Ḥill). If someone from within the Ḥaram performs iḥrām for 'Umrah, a dam (sacrifice) becomes obligatory upon him, which must be slaughtered and distributed among the poor of the Ḥaram, such as one who performs iḥrām from Kudā. His 'Umrah is considered valid, based on the statement of Ibn 'Abbās (may Allah be pleased with them both): "Whoever omits something from his ritual or forgets it, a dam is incumbent upon him." The obligation to go out to al-Ḥill for 'Umrah is so that the mu'tamir (person performing 'Umrah) combines both al-Ḥill and al-Ḥaram in his ritual, just as the pilgrim combines them by standing at 'Arafāt (which is in al-Ḥill) and then entering Makkah for ṭawāf and other rites. However, the mu'tamir's ignorance of the ruling does not waive the dam from him.