“Cast me not off” is a more traditional, poetic, and biblical way of phrasing the request, following an older word order commonly found in religious or literary texts. On the other hand, “cast me off not” sounds unnatural in modern English because the adverb “not” typically follows the auxiliary verb rather than appearing at the end. Inverting it this way disrupts the natural flow of the sentence. So, while “cast me not off” is an older, poetic structure, “do not cast me off” would be the standard modern equivalent If you’re looking to improve your understanding of grammar and structures like these, you can book a lesson with me, and we can dive deeper into these topics together!

If this is the King James version just remember you're reading English from over 400 years ago, so a lot of it will not be the way people speak and write now.