Kitab-i-Aqdas/Elder67

God has ordained for every man who desires to leave his country that he appoint a time to his spouse for his return. If he returns and keeps his promise, he has followed the command of his Master. He is one of the doers of good. By the Pen of Command it is ordained.

If he had a true excuse (for not keeping his promise), he must inform his spouse and do his utmost to return to her. If these two conditions are not fulfilled, she must yet delay nine full months. After she has completed them, there is no harm in her choosing (another) husband. If she is patient, (it is well, for) He loves patient women and patient men. Perform My commands and follow not every polytheist, who according to the Tablet is a sinner.