Is There Any Qur’anic Evidence the Hadith is a Valid Part of Islam?

If Allah had intended for us to follow the Hadith, he would have included them in the Qur’an. Since I’m pretty sure He didn’t forget to do so, is there any Qur’anic…

How Should I Declare the Shahadah?

Where should I say the Shahadah? Being one’s own choice, why should it be in public? Is it just a kind of ritual practice?