מדרש על ברכות 5:2

Rabbi Tanchum said: On account of the seed of the earth, when it is commanded, (it) discharges the dew for the resurrection of the dead. From what place does it descend? From the head of the Holy One, blessed be He; for the head of the Holy One, blessed be He, is full of the reviving dew. In the future life the Holy One, blessed be He, will shake His head and cause the quickening dew to descend, as it is said, "I was asleep, but my heart waked… for my head is filled with dew, my locks with the drops of the night" (Cant. 5:2).