Sayyiduna Jabir (may Allah be pleased with him) narrates: The Prophet (peace and blessings be upon him) said: "There is no marriage without a guardian. If (the guardians) dispute among themselves, then the ruler is the guardian of one who has no guardian."
Imam al-Tabarani recorded it in al-Mu'jam al-Awsat; its chain contains a narrator, Amr bin Uthman al-Raqqi, who is matruk (abandoned), though Ibn Hibban declared him thiqah (trustworthy).
Hadith Referenceمجمع الزوائد ومنبع الفوائد / كتاب النكاح / 7516