Having witnesses for marriage is very essential without which marriage would be rendered null. If there were no witnesses, how can we give our judgment that this is a valid marriage?

Sheikh `Abdul-MajeedSubh, a prominent Azharite scholar, illustrates: “Marriage without witnesses will waste the woman’s rights. This marriage must be documented, and it is groundless if it was to be done without witnesses. It is just to keep the honour and dignity of the woman, and this won’t be achieved unless there are witness who will witness to the validity and soundness of this marriage.
A Muslim is ordered to defend his fame with all the means and not to put him/herself in suspicious situations. It was narrated that the Prophet (peace and blessings be upon him) was walking with this wife Safeyyah (may Allah be pleased with her) and some companions saw him, but they did not verify who was waking with him. He called them and said: Come in, this is Safeyyah my wife. The same must be said for any marriage carried out without witnesses. Marriage should have all essential parts that would make it valid and sound.”