Sayyidah Aishah Siddiqah (may Allah be pleased with her) narrates: The Prophet (peace and blessings be upon him) said: "There is no marriage without a guardian (wali) and two upright witnesses."
Imam al-Tabarani recorded it in al-Mu'jam al-Awsat; its chain contains a narrator, Uthman bin Abd al-Rahman al-Waqqasi, who is matruk (abandoned).
Hadith Referenceمجمع الزوائد ومنبع الفوائد / كتاب النكاح / 7523