The Messenger of Allah ﷺ said: The marriage of a woman who marries without the consent of her guardians is void. (He said these words) three times. If there is cohabitation, she gets her dower for the intercourse her husband has had. If there is a dispute, the sultan (man in authority) is the guardian of one who has none. (Using translation from Abū Dāʾūd 2083)   

قَالَ رَسُولُ اللَّهِ ﷺ «لَا تُنْكَحُ الْمَرْأَةُ بِغَيْرِ إِذْنِ وَلِيِّهَا فَإِنْ نُكِحَتْ فَنِكَاحُهَا بَاطِلٌ ثَلَاثَ مَرَّاتٍ فَإِنْ أَصَابَهَا فَلَهَا مَهْرُهَا بِمَا أَصَابَ مِنْهَا فَإِنِ اشْتَجَرُوا فَالسُّلْطَانُ وَلِيُّ مَنْ لَا وَلِيَّ لَهُ»