קבלה על ישעיהו 59:21

We have learned.... that the Torah that we need to learn on this night [Leyl Shavuot] is the Oral Torah, so that they may be purified together from the wellspring of the deep stream. Afterward, on this day [of Shavuot] Written Torah will come join her and they will be as one, as one couple above. Then it is proclaimed about him (Isaiah 59:21) 'And this is for Me My covenant with them said YHVH: My spirit that is upon you and My words I have put in your mouth (will not depart from your mouth, nor from your children's mouths...now and forever)'.