Is it permissible for the maternal grandfather or the paternal grandfather of the woman to bear witness to the marriage contract?

The majority of scholars stipulate that for a marriage (nikah) to be valid, there must be the testimony of two just, Muslim witnesses. It is permissible for the witness to be the woman's grandfather. Some jurists have prohibited the testimony of the ascendants or descendants of the spouses, or the guardian, due to suspicion (tuhmah). However, others hold that their testimony is valid because marriage is not solely a right belonging exclusively to one party, but rather it involves both rights and obligations simultaneously for both.