What is the ruling regarding a man who said to his wife, "You are threefold divorced if you do such and such," and she did it? Does one divorce occur or three? Is verbal reconciliation sufficient to take her back? And what is the ruling on marital relations thereafter if a triple divorce has occurred and they are unaware?

If you made your wife's triple divorce contingent on a specific action, and she then performed it, the triple divorce has occurred according to the majority of scholars. She cannot be taken back unless she marries another man willingly, and he divorces her after consummating the marriage. Cohabiting with her after the triple divorce is forbidden and considered adultery, unless it was done out of ignorance.

However, according to the school of thought of Sheikh al-Islam Ibn Taymiyyah, if you did not intend divorce, then no divorce is binding upon you, but an expiation for breaking an oath is sufficient. If you did intend divorce, then a single divorce becomes binding, and you can take her back before her waiting period ends, provided this divorce does not complete the three divorces.