All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His Slave and Messenger.
If his marriage fulfilled all conditions by which marriage is held valid, as regards the guardian, the witnesses, and all other conditions, then it is a valid marriage, and its validity is not affected by his failure to make expiation for his oath before it. For further information about the conditions of valid marriage, please refer to Fatwa 83629.
Allaah Knows best.