What is the ruling on delaying a prayer beyond its prescribed time, swearing by Allah not to repeat it despite repeated instances of doing so, and raising one's voice during prayer?

You are afflicted with Waswasah (obsessive whisperings), and its cure is to ignore it and pay no attention to it. So, if you perform ablution, your prayer is valid, and you do not need to repeat it. Do not raise your voice when reciting in prayer; it is sufficient for you to hear yourself. Beware of going along with Waswasah, for it is from Satan. As for swearing not to repeat the prayer and then repeating it, you are required to offer an expiation for breaking an oath.