Quran 2:230 — The Heifer (Al-Baqarah)

If he divorces her (for the third time), it is unlawful for him to remarry her, unless she marries another man, then he divorces her. The first husband can then remarry her, so long as they observe GOD's laws. These are GOD's laws; He explains them for people who know.

[2:229] Divorce may be retracted twice. The divorced woman shall be allowed to live in the same home amicably, or leave it amicably. It is not lawful for the husband to take back anything he had given her. However, the couple may fear that they may transgress GOD's law. If there is fear that they may transgress GOD's law, they commit no error if the wife willingly gives back whatever she chooses. These are GOD's laws; do not transgress them. Those who transgress GOD's laws are the unjust.

[2:231] If you divorce the women, once they fulfill their interim (three menstruations), you shall allow them to live in the same home amicably, or let them leave amicably. Do not force them to stay against their will, as a revenge. Anyone who does this wrongs his own soul. Do not take GOD's revelations in vain. Remember GOD's blessings upon you, and that He sent down to you the scripture and wisdom to enlighten you. You shall observe GOD, and know that GOD is aware of all things.