What is the ruling on saying: "Divorce me if you don't agree to marry me before a month from now"?

Uttering "I divorce you" to oneself does not entail anything, because divorce does not occur merely by inner thoughts; rather, it must be pronounced. Furthermore, divorcing a woman who is not one's wife does not take effect because her marital bond has not yet been established. If you doubt what you pronounced after the legal marriage contract, nothing is binding on you, because the original state is the continuation of the marital bond.