Is it valid to marry under a heretical imam, with two witnesses present and knowledge of the heresy at the time of the marriage contract?

Bearing witness to the marriage contract is a condition for its validity, and it requires the testimony of two men. The testimony of one man and one woman is not sufficient. If the man bearing witness to the contract is one of the proponents of disbelieving innovations (bid'ah mukaffirah), his testimony is not valid. However, if his innovation is not of the disbelieving kind, his testimony is permissible. If this man was the one who officiated the marriage contract, then it is not valid for him to be a witness to it. Bearing witness at the time of the contract is the view of the majority (Jumhur), while the Malikis differed, holding that bearing witness at the time of the contract is recommended (mustahabb) and becomes obligatory at the time of consummation (dukhul) if no witnesses were present at the time of the contract.