Al-Baqara 2:230

Thereafter, if he divorces her [the third time], it is not lawful for him to remarry her until she marries another man[122]. Should he divorce her, then there is no sin on them to return to each other[123], provided that they would maintain the limits ordained by Allah. These are the limits ordained by Allah, which He makes clear to people who understand.

[122] With the intention of permanence, not merely in order to return to the previous husband.
[123] Going back to her earlier husband if the divorce from her subsequent husband is sealed.

And if he has divorced her [for the third time], then she is not lawful to him afterward until [after] she marries a husband other than him.[90] And if he [i.e., the latter husband] divorces her [or dies], there is no blame upon them [i.e., the woman and her former husband] for returning to each other if they think that they can keep [within] the limits of Allāh. These are the limits of Allāh, which He makes clear to a people who know [i.e.,understand].

[90] With the intention of permanence, not merely in order to return to the previous husband.

230. And if he has divorced her (the third time), then she is not lawful unto him thereafter until she has married another husband. Then, if the other husband divorces her, it is no sin on both of them that they reunite, provided they feel that they can keep the limits ordained by Allâh. These are the limits of Allâh, which He makes plain for the people who have knowledge.

And if he hath divorced her (the third time), then she is not lawful unto him thereafter until she hath wedded another husband. Then if he (the other husband) divorce her it is no sin for both of them that they come together again if they consider that they are able to observe the limits of Allah. These are the limits of Allah. He manifesteth them for people who have knowledge.