Kabbalah zu Schir haSchirim 7:2

It is called “Purim” because of Yom HaKippurim [which can be read as “the day that is like Purim”], for, in the future, people will rejoice on Yom Kippur, and will transform its required afflictions to delight. Although the Divine Presence forbade the wearing of shoes on Yom Kippur, at that time people will quote the verse, “How beautiful are your footsteps in sandals, O prince’s daughter” (Shir HaShirim/Song of Songs 7:2), and pleasure, joy, and much good will happen on that day – this will be the case in the time of the coming Redemption.