Why does the Torah write that "Lemech (not to be confused with Kayin's grandson) bore a son," and not that he bore Noach, as it writes by all the other generations?
Rashi: Because "Ben" is a derivative of the word 'Binyan' (building), to hint that the entire world would be built from him.
Da'as Zekenim: Because Mesushelach advised him not to name him promptly, lest witches harm him.
QUESTIONS ON RASHI
Rashi writes: "'And he had a son' (va'Yoled Ben) - from whom the world was built (from root 'Banah')." Why does Rashi explain in this way?
Gur Aryeh: Why does the Torah use the word "Ben" only here; weren't all of these sons? Rather, here it implies that Noach would build up the world. In fact, even the meaning "son" stems from the idea of building, for a child represents building upon his father's foundation. 1
Ibn Ezra to 16:2. Gur Aryeh continues - The same is true of the word for "daughter," as we see from the plural form, "Banos."
