Kabbalah zu Bereschit 12:5

And when Abraham our father, may he rest in peace,/ looked, saw, understood, probed,/ engraved and carved,/ He was successful in creation,/ as it is written,/ "And the souls that they made in Haran" (Genesis 12:5)./ Immediately there was revealed to him the Master of all,/ may His name be blessed forever,/ He placed him in His bosom, and kissed him on his head,/ and He called him,/ "Abraham my beloved" (Isaiah 41:8)./ He made a covenant with him/ and with his children after him forever,/ as it is written,/ "And he believed in God, and He considered/ and He considered it righteousness" (Genesis 15:6)./ He made with him a covenant/ between the ten fingers of his hands - / this is the covenant of the tongue,/ and between the ten toes of his feet - / this is the covenant of circumcision,/ And He bound the 22 letters of Torah to his tongue/ and He revealed to him His mystery/ He drew them in water,/ He flamed them with fire,/ He agitated them with Breath,/ He burned them with the seven [planets]/ He directed them with the twelve constellations.

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!