What is the ruling on swearing by "By God Almighty, if you don't take this money, I will never speak to you in my life" in the event that the money is not taken?

It is obligatory to break this oath, and it is forbidden [to keep it]. An expiation for breaking an oath is also obligatory because it is an oath to commit something forbidden, which is not speaking to one's sister. It is stated in "Maṭālib ʾUlī al-Nuhā": "And whoever swears an oath to commit something forbidden, or to neglect an obligation, it is obligatory for him to break it, so that he does not sin by committing the forbidden act or neglecting the obligation, and keeping it becomes forbidden."