Commentary for Deuteronomy 32:2

יערף כמטר לקחי MY DOCTRINE DROPPETH AS RAIN — This is the evidence that ye will have to give: that in your presence I declare that the Torah which I gave to Israel (לקחי) is life to the world as the rain which is life to the world (cf. Sifrei Devarim 306:17) — even as the heavens drop down dew and rain.

He states My doctrine shall drop as the rain,³Verse 2. for that which he took from the heavens [i.e., the Written Torah]⁴Abusaula. and His commandment upon the earth [i.e., the Oral Torah]⁴Abusaula. shall drop upon Israel and distill upon them like dew. When I shall call the name of the Eternal in the heavens ascribe ye greatness to our G-d⁵Verse 3. on earth — and he is speaking to all Israel [for it is they who are on earth]. Similarly, the “stone” of Joshua²Joshua 24:27. See Vol. I, p. 390. alludes to this earth, for from thence is the Shepherd, the Stone of Israel.⁶Genesis 49:24. See Ramban ibid., in my Hebrew edition pp. 273-274. I have already explained it.⁶Genesis 49:24. See Ramban ibid., in my Hebrew edition pp. 273-274. So also, The stone which the builders rejected has become the chief corner-stone. This is the Eternal’s doing etc.⁷Psalms 118:22-23. Therefore, Joshua said, Behold, this stone shall be a witness against us.²Joshua 24:27. See Vol. I, p. 390. And so also, For behold the stone that I have laid before Joshua; upon one stone are seven facets etc.⁸Zechariah 3:9. Reference here is to Joshua the High Priest, who ministered in the early period of the Second Temple. The student learned in the mysteries of the Cabala will understand.

יערף במטו לקחי, "May my teaching drop like the rain." We may understand these words of Moses as being similar to the statement in Avot 3,21: "if there is no flour there will be no Torah, etc." The message is that just as the Israelites require rainfall for their physical survival so they require words of Torah instruction for their spiritual survival. The meter of the verse is: "May my teaching drop like rain." G'd does not expect His people to study Torah until He has provided physical sustenance for them. Conversely, you may conclude from Moses' words that if words of Torah will not drop from the people's lips, G'd in turn is not anxious to provide rain for them. This is precisely what Rabbi Eleazar ben Azaryah meant in Avot when he said on the one hand: "if there is no flour there is no Torah; if there is no Torah there will be no flour." Accordingly, you can understand what Rabbi Eleazar ben Azaryah said in this vein: "if you observe that there is not enough flour, know that the reason is that there is not enough Torah study." The reason that Moses employs the simile of rain falling for describing Torah study is because just as rain falls in droplets so Torah is absorbed a little at a time.