Suddenly, the word of HaShem came to him, saying, “That one will not inherit you; only the one who shall come forth from within you shall inherit you.” And He took him outside, and said, “Gaze, now, up at the heavens and count the stars if you are able to count them!”
Why did He want Avrom to gaze up at the heavens and count the stars? HKB”H could have simply promised Avrom that his offspring would be as numerous as the stars without making him leave his tent.
Ohr HaChaim HaKadosh states that HaShem had already promised Avrom that his offspring would be too numerous to count (ibid. 13, 16): —I will make your offspring as the dust of the earth so that if one can count the dust of the earth, then your offspring, too, can be counted. So, why did Avrom feel compelled to voice the complaint: “הן לי לא נתתה זרע” --see, to me You have given no offspring?
The answer provided by the Ohr HaChaim HaKadosh: HaShem’s initial promise to Avrom is made in terms of the “dust of the earth.” This is usually a designation reserved for lowly characters devoid of kedushah—as illustrated by the term “am ha’aretz.” Hence, Avrom was not satisfied with HaShem’s initial promise; he desired offspring of upstanding spiritual and moral character—tzaddikim. To allay this concern, the promise was repeated with reference to the heavenly stars. We see from a pasuk in Daniel (12, 3) that tzaddikim are compared to stars. Thus, his mind was set at ease.
The Ohr HaChaim HaKadosh is not totally satisfied with this answer, however. For, we find in the Midrash (B.R. 41, 9) that even HaShem’s promise to Avrom that his offspring would be as numerous as the “dust of the earth” was intended in a very positive sense: just as the dust of the earth is found everywhere on earth, so, too, will your offspring be found in every corner of the earth; just as dust is enhanced and enriched only by water, so, too, Yisrael are only enriched in the merit of Torah—which is compared to water. Hence, we see that even the promise that his offspring would resemble the “dust of the earth” was intended in a positive sense and not in a negative sense. Thus, we need to explain why Avrom felt compelled to add the request: ” הן לי לא נתתה זרע “—I desire offspring that will resemble me.
The Ohr HaChaim HaKadosh concludes that before hearing HaShem’s second promise—comparing his offspring to the heavenly stars— Avrom believed that the comparison to the “dust of the earth” was negative and derogatory. Therefore, he beseeched HaShem: “הן לי לא נתתה זרע” —I desire offspring that will resemble me. After hearing the second promise, however—that he would merit having exalted offspring comparable to the stars in the heavens—he realized that the initial promise also alluded to the greatness of his future offspring. For this reason, our blessed sages also interpreted the analogy to the “dust of the earth” in very positive terms
