Narrated 'Aishah (RA):

Allah's Messenger (ﷺ) said: "If anyone married without the consent of her guardian, her marriage is invalid. If there is cohabitation, she is entitled to the dowry, due to the sexual intercourse made lawful with her. If there is a dispute (between her guardian), the ruler is the guardian of one who has no guardian." [Reported by al-Arba'a except an-Nasa'i. Abu 'Awanah, Ibn Hibban and al-Hakim graded it Sahih (authentic)].

وَعَنْ عَائِشَةَ رَضِيَ اَللَّهُ عَنْهَا قَالَتْ : قَالَ رَسُولُ اَللَّهِ ‏- صلى الله عليه وسلم ‏-{ أَيُّمَا اِمْرَأَةٍ نَكَحَتْ بِغَيْرِ إِذْنِ وَلِيِّهَا, فَنِكَاحُهَا بَاطِلٌ, فَإِنْ دَخَلَ بِهَا فَلَهَا اَلْمَهْرُ بِمَا اِسْتَحَلَّ مِنْ فَرْجِهَا, فَإِنِ اشْتَجَرُوا فَالسُّلْطَانُ وَلِيُّ مَنْ لَا وَلِيَّ لَهُ } أَخْرَجَهُ اَلْأَرْبَعَةُ إِلَّا النَّسَائِيَّ, وَصَحَّحَهُ أَبُو عَوَانَةَ , وَابْنُ حِبَّانَ وَالْحَاكِمُ [1]‏ .‏