The saying of Allah, exalted be His praise: "Then when they reach their (waiting) term, either retain them in a good manner or part with them in a good manner, and take as witnesses two upright men from among you." [Surah al-Talaq: 2]
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الشهادات / Q20525
Rafi' bin Khadij (may Allah be pleased with him) said: A man of the Ansar was found killed in the morning at Khaybar. His heirs mentioned this to the Prophet (peace and blessings be upon him). He (peace and blessings be upon him) asked: "Do you have two witnesses who will testify to this killing?" They said: O Messenger of Allah (peace and blessings be upon him)! No Muslim was present there; there are only Jews there, and they are capable of doing even greater than this.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الشهادات / 20525
Sayyidah Aishah (may Allah be pleased with her) said that the Messenger of Allah (peace and blessings be upon him) said: "There is no marriage without a guardian and two upright witnesses. If they dispute, then the ruler is the guardian of the one who has no guardian. If she married (herself), her marriage is void."
(b) Hadrat Umar bin al-Khattab (may Allah be pleased with him) said: Without a guardian and two upright witnesses, marriage is void.
(c) The report that Hadrat Umar bin al-Khattab (may Allah be pleased with him) permitted the testimony of a man together with women in marriage, narrated by Hajjaj bin Artah from Ata, is not sound.
Ata's narration from Umar is munqati' (broken), and Hajjaj bin Artah is not used as proof; the mursal report of Ibn al-Musayyib from Umar (may Allah be pleased with him) is more authentic.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الشهادات / 20526
Ibrahim (may Allah have mercy on him) said that the testimony of women is not permissible in hudud and divorce. He said: Divorce is the severest of the hudud.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الشهادات / 20528