Isaiah 1:10-17 chronicles the time before Ezra and Nehemiah when Judah observed the feasts, yet in a wrong spirit and with reprehensible conduct. Isaiah preached this to the Jews about one hundred years before they went into captivity to Babylon.
This is a clear indictment of their spirit and attitude, advancing strong proof of why God later said through Ezekiel that Israel and Judah went into captivity because of idolatry and Sabbath-breaking (Ezekiel 20:12-21).
There is no reason to believe that, just because God says "your" new moons and "your" feasts, they were not the ones He appointed, at least in name. He could rightly call them "your feasts" because their keeping of them was so abominable that they bore no resemblance to His intent in commanding them to be observed. They were completely discordant with His character, as the listing of their sins shows.
He calls their giving of offerings, which were part of the spiritual aspects of keeping the feasts, vain and trampling His courts. He designates their prayers as an abomination, and their keeping of the feasts wearying to Him. Clearly, He had "had it up to here" with their Sabbath and festival observances. Have we examined our conduct recently in relation to our attitudes, approaches, and expectations for the Feast?