The Midrash comments that Yaakov took twelve stones, symbolizing the nation that he would soon establish. The twelve stones represented the twelve tribes which were to coalesce into a unified nation. Yaakov said, “I knew that a great nation would be established. Avraham did not establish it and neither did my father, Yitzchak. If these twelve stones meld together to become one, then it is a sign that I will be the one who will establish this great nation.”
Yaakov Avinu’s simile is enigmatic. If one person, Yaakov, were to establish a nation via the birth of twelve tribes, then he should have taken a simple stone which would transform into twelve little stones. How do twelve stones becoming a single stone represent the prospective nation of twelve tribes?
Yalkut Yehudah infers from this Midrash that Yaakov was seeking a sign from Heaven. This sign would give him the key for establishing a nation that could withstand the vicissitudes of time and endure the various trials it would eventually confront. He was told that “achdus”, unity and harmony, among the twelve tribes would enable them to fuse into one strong unit, so that the nation would endure. The kiyum, ultimate existence of our people, is dependent upon our solidarity under one banner — the banner of Torah.