פירוש על קידושין 103:6

Rav also learns from the story that one cannot betroth with stolen goods. In the story, the man uses something he took from the women and it was sabbatical produce. The kiddushin are valid only because the produce he stole was sabbatical produce which is considered ownerless. During the sabbatical year, anyone can take the produce from the field. Had it not been the sabbatical year, they would not have been betrothed because one cannot use stolen goods to betroth.