“David also married Ahinoam of Jezreel. Both of them became his wives. Saul had given Michal his daughter, David’s wife, to Palti son of Laish, who was of Gallim.”
In a strange twist of fate, David lost 1 wife Michal, but got 2 others. David had originally married Michal, Saul’s daughter. However, because of the dispute between David and Saul, Saul seems to take her back and give her to Palti, who is not mentioned elsewhere whose father was Laish, which is also the name of a town. However, during this period in the wilderness, David married Ahinoam who was a woman of Judah also. Both of these new wives were from Judah. Polygamy in a strong patriarchal society never posed a problem. Anyway, Abraham with a wife and a female servant as well as Jacob with his 2 wives and 2 female servants are the ones who helped produce the clan of Israel. Thus David falls into this same category with multiple wives. Finally, the inspiration for polygamy for Christian groups such as the Mormons stems from these biblical stories.