Romans 14:5
"One man esteemeth one day above another: another esteemeth every day alike. Let every man be fully persuaded in his own mind."
Cross References (ranked by relevance)
Romans 14:23
And he that doubteth is damned if he eat, because he eateth not of faith: for whatsoever is not of faith is sin.
1 Corinthians 8:7
Howbeit there is not in every man that knowledge: for some with conscience of the idol unto this hour eat it as a thing offered unto an idol; and their conscience being weak is defiled.
Romans 14:14
I know, and am persuaded by the Lord Jesus, that there is nothing unclean of itself: but to him that esteemeth any thing to be unclean, to him it is unclean.