The point is there is NO alteration or command in Scripture for any day other than the seventh day.
This is also not true.
Isaiah 1:10-14
Hear the word of the LORD, ye rulers of Sodom;
give ear unto the law (Towrah) of our God, ye people of Gomorrah.
To what purpose
is the multitude of your sacrifices unto me? saith the LORD: I am full of the burnt offerings of rams, and the fat of fed beasts; and I delight not in the blood of bullocks, or of lambs, or of he goats.
When ye come to appear before me, who hath required this at your hand, to tread my courts? [Moses]
Bring no more vain oblations; incense is an abomination unto me;
the new moons and sabbaths, the calling of assemblies,
I cannot away with; it is iniquity, even the solemn meeting.
Your new moons and your appointed feasts my soul hateth: they are a trouble unto me; I am weary to bear
them.
[this Torah seems to be a little different than that given at Sinai]
Lamentation 2:5-7
The Lord was as an enemy: he hath swallowed up Israel, he hath swallowed up all her palaces: he hath destroyed his strong holds, and hath increased in the daughter of Judah mourning and lamentation.
And he hath violently taken away his tabernacle, as if it were of a garden: he hath destroyed his places of the assembly: the LORD hath caused the solemn feasts and sabbaths to be forgotten in Zion, and hath despised in the indignation of his anger the king and the priest.
The Lord hath cast off his altar, he hath abhorred his sanctuary, he hath given up into the hand of the enemy the walls of her palaces; they have made a noise in the house of the LORD, as in the day of a solemn feast.
The LORD hath purposed to destroy the wall of the daughter of Zion: he hath stretched out a line, he hath not withdrawn his hand from destroying: therefore he made the rampart and the wall to lament; they languished together.
Her gates are sunk into the ground; he hath destroyed and broken her bars: her king and her princes
are among the Gentiles:
the law is no more; her prophets also find no vision from the LORD.
17.
The LORD hath done that which he had devised; he hath fulfilled his word that he had commanded in the days of old: he hath thrown down, and hath not pitied: and he hath caused
thine enemy to rejoice over thee, he hath set up the horn of thine adversaries.
Hosea 2:11. I will also cause all her mirth to cease, her feast days, her new moons,
and her sabbaths, and all her solemn feasts.
Amos 8:5 & 9,10,11 is also a very interesting passage re: when will the sabbath be gone.
If the oblations, sacrifices, incense, tabernacle, the callings of assembly, the altar and his sanctuary are all prophetically decreed to be cast off and violently taken away, by God himself, does it not follow that when these are cast off and violently taken away, that the sabbaths and feast days that are mentioned along side these would be included as well?