Is it true that Prophet Ayyub (peace be upon him) vowed to strike his wife one hundred times if Allah cured him, and why did he vow that?

The exegetes mention the story of Ayyub's oath to flog his wife a hundred lashes. However, no authentic marfu' hadith explains the reason for this oath. Rather, it is mentioned in the interpretations of some of the Tabi'in, who differed on the matter. Nevertheless, most of them said: Ayyub's wife asked him to utter an unlawful word that Iblis whispered to her. So, Ayyub swore that if Allah cured him, he would punish her. Then Allah commanded him to take a bundle of a hundred stalks and strike her with it once, so that he might fulfill his oath without breaking it.