After divorce from a consummated marriage, a Muslim woman

After a divorce from a consummated marriage, a Muslim woman must observe iddat, ordinarily three menstrual courses, or until delivery if she is pregnant. She cannot lawfully remarry during that period, because iddat ensures certainty of paternity.

She may remarry once iddat is over, so there is no permanent bar. Immediate remarriage is open only where the marriage was never consummated, when no iddat of divorce is required.