וּבְנֵי יִשְ ׂרָ אֵל פָּרוּ וַיִּשְ ׁרְ צוּ וַיִּרְ בּוּ וַיַּעַצְמוּ בִ ּמְ אֹד מְ אֹד וגו' (א, ז)
And the children of Yisroel were fruitful and multiplied and became very strong... (1:7)
A Baal Gaivoh Must Lower Himself:
Rav Moshe Leib of Sassov zy”a (quoted in Sefer Mishnas HaRamal) explains that this pasuk contains a hint that a haughty person must lower himself in humility and subjugation.
He explains that the words “m’od m’od” are an allusion to the Mishnah’s statement (Avos 4:8) that one should be “very, very lowly of spirit.” Thus, the pasuk means that when Klal Yisroel “was fruitful and multiplied and became very strong” and began to feel big and powerful, they had to be “m’od m’od” – they had to lower themselves by engaging in acts of humility.
Humility Creates Goodness:
Sefer Zichron Shmuel (written by a student of the Chozeh of Lublin zy”a) also explains the words “m’od m’od” to be a reference to the Mishnah that says that one should be very, very humble. He explains this Mishnah by citing Meforshim who say that although the Rambam states (Hilchos Dayos 2:3) in regards to all other middos that one should take “the middle road”, and should not go to any extreme, when it comes to the middah of anavah, one should go to the utmost extreme and be as humble as possible.
The moon is a symbol of humility, as it signifies that if a person recognizes his smallness and lowly state, he will merit an abundance of goodness. This lesson is learned from the Gemara (Chulin 60B) that says that the moon complained that the sun was the same size as it and said to Hashem, “It is impossible for two kings to wear one crown.” Hashem replied, “If so, shrink yourself.” The moon then shrunk itself and, as compensation, Hashem said that righteous men would be called in its name, such as Yaakov Hakatan, Shmuel Hakatan and Dovid Hakatan. (They are also called “small”, just like the moon was made small.)
Rashi adds (Bereishis 1:16) that when Hashem diminished the moon, He added many stars to its entourage in order to appease it. Rashi also writes (ibid 10:25) that one of Ever’s sons was named “Yaktan”, which has a root of “katan” (small) because he was a humble man who made himself small, and because of his humility, he merited being the forebearer of many families.
The reason humility creates so much blessing is seen in the words of Chazal (Brachos 40A): “An empty vessel can hold things but a full vessel cannot hold anything.” If a person feels “full” and thinks he is great, he cannot be a vessel to contain any holiness or blessing. But if one considers himself empty and small, he can be a vessel of holiness and blessing. The more one minimizes himself, the more Hashem can place His presence within him, and the more blessing he can receive.
Accordingly, the pasuk can be understood as saying that Klal Yisroel became strong in the middah of “m’od m’od” – the middah of humility – and, through this, “the land became full of them”. Since they were humble, they merited all of the blessings of the land, just like the moon that merited a large entourage of stars in the merit of minimizing itself.