מדרש על שמות 25:19

It is written: One cherub at one end, and one cherub at the other end (ibid. 37:8). Just as the heavens open their treasures to the earth, as is said: The Lord will open unto thee His good treasure the heaven to give the rain of thy land in its season (Deut. 28:12), so the Shekhinah was placed above the two cherubim, which were face-to-face. And Israel was exalted through the tablets, as it is said: On the one side and on the other were they written (Exod. 32:15).