Sefer HaBahir 59

1[Rabbi Berachiah continued,] "And what is 'heavens'? It teaches that the Blessed Holy One mixed together fire and water, measured them this with this, and made from them a beginning of His words. As is written, 'The beginning of your words is truth' (Psalms 119:160). Thus, it is written, 'heavens [שמים]' — 'placed water' [שם מים] — fire and water." They said to him, "Until here, 'The One Who makes peace in His heights' (Job 25:2). He gave peace and love between them, and He will give peace and love between us."