Variantly: "Listen, O heavens": An analogy: a father, whose son has corrupted his ways. First he complains to his brothers, then to his companions, then to his neighbors, then to his kin. He does not leave off complaining until he says: "To whom shall I complain? — to the heavens!" This is the intent of "Listen, O heavens."
Variantly: "Listen, O heavens": Not only are the righteous righteous, but they "broaden" the world in which they live. For when Israel do G-d's will, what is written of them? (Devarim 28:12) "The L-rd shall open for you His goodly treasure trove, the heavens," "opening" connoting "broadening," as in (Bereshith 29:31) "and the L-rd opened her womb." And not only are the wicked wicked, but they "constrict" the world in which they live. For when they do not do G-d's will, what is written of them? (Ibid. 11:17) "and He will hold back the heavens," connoting "constricting," as in (Bereshith 20:18) "and the L-rd held back every womb."