וְהָיָ֗ה מִֽדֵּי־חֹ֙דֶשׁ֙ בְּחָדְשׁ֔וֹ וּמִדֵּ֥י שַׁבָּ֖ת בְּשַׁבַּתּ֑וֹ יָב֧וֹא כָל־בָּשָׂ֛ר לְהִשְׁתַּחֲוֺ֥ת לְפָנַ֖י אָמַ֥ר יְהוָֽה׃
Et il arrivera constamment, à chaque néoménie, à chaque sabbat, que toute chair viendra se prosterner devant moi, dit l’Éternel.
Rabbeinu Bahya
Rabbi Saadyah Gaon explains the word שדי as meaning that He makes up any shortfall, i.e. supplies די, adequacy. Yet another explanation offered for this word relates it to Isaiah 66,23 מדי חדש בחדשו, ”from month month.” It means that something is constant, repeats itself endlessly. The name Shaddai then describes G’d’s eternal nature.
Ibn Ezra
while revere My sanctuary also denotes the jubilee year, as it is written, “it will be sanctified by you” [25:12]. In my opinion, “observe my sabbaths” is mentioned on account of having mentioned “to prostrate yourselves upon it” [:1], along the lines of “every Sabbath, all flesh shall come to bow to the ground before me” [Isaiah 66:23]. In other words: You must come every Sabbath to prostrate yourselves before Me — not on some ornamental stone, but only in My sanctuary. Thus, Scripture mentions the choice day (which was chosen for the service of God, as I have explained [comment on Genesis 2:3]), as well as the choice place.
Rashi
The judgment of the wicked in Geihinnom lasts for twelve months, as it is stated (Isaiah 66:24, 23), "Nor their fire be quenched"; "And new moon after new moon, and Shabbat after Shabbat, all flesh shall come" - this implies even those condemned to it: Just like Shabbats are according to their count, so too are months according to their count. And this is certainly speaking about the sinners of Geihinnom, since written (above) [below] it is, "They shall go out and gaze on the corpses of the men who rebelled against Me." So is it taught in Seder Olam (Chapter 6).