For even though the heavens were created on the first day, they were still liquid, but they congealed on the second day in response to the Holy One’s roar, when he said “Let there be a firmament.” This is what the verse means (Job 26:11): “The pillars of heaven tremble” – all through the first day, and on the second [they were] “Astounded at His blast” like a person who is stunned and freezes from the roar of someone threatening him.
שאף על פי שנבראו שמים ביום ראשון, עדיין לחים היו, וקרשו בשני מגערת הקדוש ברוך הוא באומרו יהי רקיע וזהו שכתוב (איוב כו יא) עמודי שמים ירופפו כל יום ראשון.