All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad (ﷺ) is His slave and Messenger.
We congratulate you on the blessing Allah has bestowed upon you in entering Islam, and we ask Him, Mighty and Majestic, to grant you steadfastness upon it until death. We advise you to be diligent in seeking beneficial knowledge, performing righteous deeds, keeping the company of righteous women, and attending gatherings of good, for these are among the means of remaining firm upon the truth.
As for the marriage contract witnessed by this man [i.e., where the guardian himself was one of the witnesses] — it is not valid, as some scholars have explicitly stated, because it would constitute a person's testimony regarding his own act.
However, witnessing in marriage is not limited to the person who was specifically asked to serve as a witness and who signed the official documents; rather, everyone who was present at the marriage contract and witnessed it is [also] considered a witness, even if he was not asked to be a witness on the official papers. Likewise, if the marriage becomes well-known and publicly announced, it is valid even if two witnesses were not present to witness the contract itself — this being the view held by a number of scholars
. Shaykh al-Islam [Ibn Taymiyyah]
said in *al-Ikhtiyarat al-Fiqhiyyah*: “There is no doubt that a marriage accompanied by public announcement is valid even if two witnesses did not witness it.” [End of quote]
Accordingly, if some deficiency occurred in the witnessing of the marriage — such as the guardian (wali) witnessing the contract along with another witness — but there were, in fact, a number of people present at the contract at the time of the witnessing, or the marriage was subsequently publicly announced, then in this case the marriage is valid, and it is not affected by the fact that the guardian was one of the two witnesses.
As for if no one besides the guardian and one witness with him was present at the contract, and it was not subsequently publicly announced, then it should be rectified by making a new contract.
Allah Knows best.