"Her first husband who sent her away may not marry her again"—Deuteronomy 24:4.
It is forbidden for a man to remarry a woman he divorced if she has remarried [and subsequently been divorced again or widowed] in the interim.
Negative Commandment 356 (Digest)
Remarrying a Divorced Wife Who Remarried in the Interim
"Her first husband who sent her away may not marry her again"—Deuteronomy 24:4.
It is forbidden for a man to remarry a woman he divorced if she has remarried [and subsequently been divorced again or widowed] in the interim.