If Jesus is a messenger in Islam why don’t muslims follow/read the Gospels?

I’ve been already told many times that Jesus is considered a messenger in Islam. That’s nice.

But then, why do muslims follow Muhammad’s words of him registered many years later in the Quran, instead of reading the direct testimonies written at the time in the Gospels? Are they not valid for you? Then why?

Thank you in advance, it’s just curiosity. I want to learn.