Although, Prophet Muhammad (pbuh) is mentioned in the O.T. several times.
Deuteronomy 18:18 "I will raise up for them a prophet like you from among their brothers; I will put my words in his mouth, and he will tell them everything I command him"
There is no mention of muhammud (swish) in the O.T. Your post confirms that.
Islamism was not invented by Muhammud (swish) until much later.