Kabbalah su Genesi 11:30

The Rav of the Yeshiva said, it is written (Breishit 11:30), "Now Sarai was barren; she had no child." When it tells us that Sarai was barren, I already know that she had no child. So why [does the verse add], "she had no child"? Rather, here is what the Rav of the Yeshiva said: She had no child born to her, but souls she had born to her, by means of the cleaving with desire. These two righteous ones [Sarai and Avram] birthed souls for converts all the time that they were at Haran, just as the righteous make [souls for converts] in Gan Eden. As it says (Breishit 12:5), "the people [literally 'the soul'] that they acquired [literally 'made'] in Haran" -- they really did create that soul!