These are the verses that I cite for why I am not especially concerned with keeping the Sabbath as such. I have friend who keeps Sunday very strictly as the day of rest. We have agreed that neither of us shall despise the other for our own position.
Rom 14:5 One man esteemeth one day above another: another esteemeth every day alike. Let every man be fully persuaded in his own mind.
Rom 14:6 He that regardeth the day, regardeth it unto the Lord; and he that regardeth not the day, to the Lord he doth not regard it. He that eateth, eateth to the Lord, for he giveth God thanks; and he that eateth not, to the Lord he eateth not, and giveth God thanks.