וַיּוֹצֵ֨א אֹת֜וֹ הַח֗וּצָה וַיֹּ֙אמֶר֙ הַבֶּט־נָ֣א הַשָּׁמַ֗יְמָה וּסְפֹר֙ הַכּ֣וֹכָבִ֔ים אִם־תּוּכַ֖ל לִסְפֹּ֣ר אֹתָ֑ם וַיֹּ֣אמֶר ל֔וֹ כֹּ֥ה יִהְיֶ֖ה זַרְעֶֽךָ׃
Y sacóle fuera, y dijo: Mira ahora á los cielos, y cuenta las estrellas, si las puedes contar. Y le dijo: Así será tu simiente.
Rashi
ויוצא אתו החוצה AND HE BROUGHT HIM FORTH OUTSIDE — Its real meaning is: He brought him outside his tent so that he could look at the stars. Its Midrashic explanation is: Go forth from (give up) your astrological speculations — that you have seen by the planets that you will not raise a son; Abram indeed may have no son but Abraham will have a son: Sarai may not bear a child but Sarah will bear. I will give you other names, and your destiny (מזל planet, luck) will be changed. Another explanation: He brought him forth from the terrestrial sphere, elevating him above the stars, and this is why He uses the term הבט ‘‘look”, when He said “look at the heavens” — for this word signifies looking from above downward (Genesis Rabbah 44:12).
Chizkuni
ויוצא אותו, it appeared to Avram in his dream as if G-d were now taking him out of his house to look at the sky.
Da'at Zekenim
כה יהיה זרעך, “so shall be your seed.” Rabbi Tanchuma son of Acha, basing himself on this phrase, commented that it is an assurance that there will never be fewer than 30 righteous people on earth at all times. He uses the word יהיה, “will be (singular),” as his proof. [The numerical value of the combined letters in that word is 30. Ed.]