It was narrated from Aishah that :
the Messenger of Allah said: “Any woman whose marriage is not arranged by her guardian, her marriage is invalid, her marriage is invalid, her marriage is invalid. If (the man) has had intercourse with her, then the Mahr belongs to her in return for his intimacy with her. And if there is any dispute then the ruler is the guardian of the one who does not have a guardian.”
حَدَّثَنَا أَبُو بَكْرِ بْنُ أَبِي شَيْبَةَ، حَدَّثَنَا مُعَاذُ بْنُ مُعَاذٍ، حَدَّثَنَا ابْنُ جُرَيْجٍ، عَنْ سُلَيْمَانَ بْنِ مُوسَى، عَنِ الزُّهْرِيِّ، عَنْ عُرْوَةَ، عَنْ عَائِشَةَ، قَالَتْ قَالَ رَسُولُ اللَّهِ ـ صلى الله عليه وسلم ـ ‏ "‏ أَيُّمَا امْرَأَةٍ لَمْ يُنْكِحْهَا الْوَلِيُّ فَنِكَاحُهَا بَاطِلٌ فَنِكَاحُهَا بَاطِلٌ فَنِكَاحُهَا بَاطِلٌ فَإِنْ أَصَابَهَا فَلَهَا مَهْرُهَا بِمَا أَصَابَ مِنْهَا فَإِنِ اشْتَجَرُوا فَالسُّلْطَانُ وَلِيُّ مَنْ لاَ وَلِيَّ لَهُ ‏"‏ ‏.‏
GradeSahih (Darussalam)
English reference : Vol. 3, Book 9, Hadith 1879
Arabic reference : Book 9, Hadith 1953