When G-d gave the Torah to the People of Israel, He said to them: "I require guarantors." Said the people: "The heaven and the earth shall be our guarantors." Said G-d: "They won't last forever." Said they: "Our fathers will guarantee it." Said He: "They are busy." Said they: "Our children will guarantee it." Said He: "These are excellent guarantors."
Mechilta D'Rashbi