זוהר בראשית — דף רמ ע”ב

The Holy One, blessed be He, first struck the guardian angels of Egypt before striking Egypt itself. When the higher angels fall, the nation below falls as well. The secret is that every miracle performed by the Holy One operated on two planes simultaneously, the upper and the lower. The miracles in Egypt acted in both the upper and lower worlds. Every victory of Israel begins first in the world of the angels above.