All of Israel are responsible for one another
(Sanhedrin, 27b, Shavuot 39)
This is to speak of the Arvut (Mutual Guarantee), when all of Israel became responsible for one another. Because the Torah was not given to them before each and every one from Israel was asked if he agreed to take upon himself the Mitzva (precept) of loving others in the full measure, expressed in the words: “Love thy friend as thyself” (as explained in Items 2 and 3, examine it thoroughly there). This means that each and every one in Israel would take it upon himself to care and work for each member of the nation, and to satisfy all their every needs, no less than the measure imprinted in him to care for his own needs.
And once the whole nation unanimously agreed and said, “We shall do and we shall hear,” each member of Israel became responsible that nothing shall be missing from any other member of the nation. Only then did they become worthy of receiving the Torah, and not before.