The fourth pillar is: Bearing witness for marriage contract. Because of the Hadith of Jabir (may Allah be pleased with him) that the Messenger of Allah (peace be upon him) said: “There is no marriage without the permission of a guardian and two upright witnesses."
At-Tirmidhy said: This Hadith is effective according to the people of knowledge from the Prophet's Companions, the Successors, and others. Witnesses should be males, Muslims, adults, upright, not from the relatives of the spouses because their testimony for the spouses is not accepted, speaking and not dumb because a dumb cannot state their testimony, and they should not be deaf because the deaf do not hear the contract and accordingly they cannot witness it. Bearing witness to the marriage contract is a caution for fear of denial.
(1) [As-Suyuty attributed it to Al Bayhaqy on the authority of `Imran ibn Al Husayn and `A'ishah (may Allah be pleased with her). He also attributed it to At-Tabarany on the authority of Abu Musa (may Allah be pleased with him). Al Albany graded it as authentic. See: Sahih Al Jami` p. 7433 and 7434-203\6].
(2) [See Hashiyat Ar-Rawd Al Murbi` 6/276 and Manar As-Sabil 157/2].