Is there a Shar’i ruling entailed by the statement, “If my wife wears indecent clothing, I will not stay with her for a single moment,” even though the speaker is not yet married? And does a slip of the tongue with unintentional words affect the Shar’i ruling?

If the tongue utters something unintentionally, then nothing is entailed by it, as it is an excusable mistake according to the Qur’an and Sunnah.

The statement: "If my wife wears revealing clothes, I will not stay with her for a single moment" does not entail anything, even if divorce was intended by it, because it is a promise of divorce that does not take effect merely by uttering it.

Controlling the tongue and mastering speech is easy by accustoming oneself to guarding the tongue, except for good.