Does divorce occur if the husband permitted his wife to go with her sister and her son, after he had conditioned her divorce on her going with the sons of his brothers or his sisters, and his intention was to threaten, not to divorce, knowing that there was a previous divorce?

Intention is crucial in oaths. If you intended to prevent your wife from going out alone with her brother’s children or her sister, or without your permission, then her going out with your sister and her son, or with your permission, does not break your oath; this is because intention specifies the general. However, if you swore to prevent her from going out absolutely, then her going out breaks your oath. If you gave her permission out of ignorance of the ruling or misinterpretation, the more preponderant opinion is that no divorce has occurred.