Deuteronomy 32:2

My doctrine shall drop as the rain, the gentle and persistent rain which brings forth fruit in abundance; my speech shall distil, gently flow, as the dew, as the small rain, mild showers, upon the tender herb, as it breaks forth from the buds in the spring, and as the showers upon the grass, upon the young vegetation. That was to be the effect of Moses' song upon the hearts of the people, like that of a mild and fructifying rain.