[Machine] The Messenger of Allah ﷺ said, "Marriage is not permissible except with a guardian, witnesses, and a righteous match." Al-Shafi'i (may Allah have mercy on him) said, "This applies even if the Prophet ﷺ is no longer alive, as most scholars agree on this point. The difference between marriage and fornication is the presence of witnesses." Al-Muzani (may Allah have mercy on him) narrated this from someone other than Al-Shafi'i (may Allah have mercy on him), from Al-Hasan, from Imran ibn Husain, from the Prophet ﷺ .  

أَنَّ رَسُولَ اللهِ ﷺ قَالَ لَا يَحِلُّ نِكَاحٌ إِلَّا بِوَلِيٍّ وَصَدَاقٍ وَشَاهِدَيْ عَدْلٍ قَالَ الشَّافِعِيُّ رَحِمَهُ اللهُ وَهَذَا وَإِنْ كَانَ مُنْقَطِعًا دُونَ النَّبِيِّ ﷺ فَإِنَّ أَكْثَرَ أَهْلِ الْعِلْمِ يَقُولُ بِهِ وَيَقُولُ الْفَرْقُ بَيْنَ النِّكَاحِ وَالسِّفَاحِ الشُّهُودُ قَالَ الْمُزَنِيُّ وَرَوَاهُ غَيْرُ الشَّافِعِيِّ رَحِمَهُ اللهُ عَنِ الْحَسَنِ عَنْ عِمْرَانَ بْنِ حُصَيْنٍ عَنِ النَّبِيِّ ﷺ