Romans 14:5

14:5 One person regards one day holier than other days, and another regards them all alike. Each must be fully convinced in his own mind.

Romans 14:22-23

14:22 The faith you have, keep to yourself before God. Blessed is the one who does not judge himself by what he approves. 14:23 But the man who doubts is condemned if he eats, because he does not do so from faith, and whatever is not from faith is sin.