Why Sunday

[Amanah]

doesn't this deal with the issue of observance of days?

Let not him that eateth despise him that eateth not; and let not him which eateth not judge him that eateth: for God hath received him. Who art thou that judgest another man's servant? to his own master he standeth or falleth. Yea, he shall be holden up: for God is able to make him stand. One man esteemeth one day above another: another esteemeth every day alike. Let every man be fully persuaded in his own mind. 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. For none of us liveth to himself, and no man dieth to himself. For whether we live, we live unto the Lord; and whether we die, we die unto the Lord: whether we live therefore, or die, we are the Lord's. For to this end Christ both died, and rose, and revived, that he might be Lord both of the dead and living. Romans 14