off the top of my head Rom 14 comes to mind.
1 Corinthians 8 about not eating meat.
Romans 2:15
since they show that the requirements of the law are written on their hearts, their consciences also bearing witness, and their thoughts now accusing, now even defending them.)
Romans 14:23
But the man who has doubts is condemned if he eats, because his eating is not from faith; and everything that does not come from faith is sin.