The writings of the prophets are a rich source of information on the New Moon, commencing with the book of Isaiah. The New Moons figure prominently at the beginning and ending of the prophecies of Isaiah. In the first chapter we read:

vs. 13 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.

vs. 14 Your New Moons and your appointed feasts my soul hates; they are a trouble unto me; I am weary to bear them.

YHVH notes His distaste with the keeping of all His holy days by His people when they do not live for Him. He tells them He does not want them to bring sacrifices because they carry no meaning for this people in sin, and yet He cannot do away with New Moons and Sabbaths. These are appointed times that He has fixed.

These people are not keeping His times in a holy manner. YHVH refers to their keeping them as YOUR New Moons and YOUR appointed Feasts . . . that He hates, is troubled by, and wearied of, as they have appropriated His times for themselves.

Isaiah concludes with the same subject as he began as recorded in the final chapter of his prophecy.

vs. 22 For as the new heavens and the new earth, which I will make, shall remain before me, says YHVH, so shall your seed and your name remain.

vs. 23 And it shall come to pass, from one New Moon to another, and from one Sabbath to another, shall all flesh come to worship before me, says YHVH.

At the end of this book of Isaiah, referring to the establishment by YHVH of His kingdom with the new heavens and the new earth, YHVH declares that all flesh will appear before Him for worship on every New Moon and Sabbath.

The prophecy begins and ends with the declaration by YHVH as to the permanency of Sabbath and New Moon observance. He cannot even do away with the observance of these times by wicked peoples, and will eventually reign victoriously by these times throughout eternity.

Truly His Word is TRUTH (John 17:17), He changes not (Malachi 3:6), and He is yesterday, today and forever the same (Hebrews 13:8).