Is it obligatory to fulfill a vow made to perform charitable acts worth 3500 Saudi riyals monthly upon employment, given that the work found was for only two months and the questioner received only 300 riyals from it, and that she left it due to intermingling and harassment, and she is now unemployed and finds it difficult to find work free of intermingling that suits her specialization as a dentist? Is it permissible for her to work in mixed-gender environments in order to fulfill the vow? And does the expiation for the vow lapse if she is financially unable to fulfill it?

If the utterance was made unintentionally, then there is nothing upon you. But if you intended the utterance without intending what results from it, then it is a conditional vow that must be fulfilled when capable. If you are unable to fulfill it, then you must offer an expiation for breaking an oath (kaffarat yamin), which is feeding ten poor persons, or clothing them, or freeing a slave. And whoever cannot find these, then fasting for three days, based on the saying of the Prophet, peace and blessings be upon him: "Whoever makes a vow and does not specify it, its expiation is the expiation of an oath. And whoever makes a vow that he cannot fulfill, its expiation is the expiation of an oath." It is not obligatory to work in mixed environments where the boundaries of Allah are not observed.