Мидраш к Бамидбар 29:17

Moses appealed to the Holy One Blessed be He: L-rd of the universe, since I am departing from the world in such exaltation, show me a trustworthy man, who will go forth before them in peace, as it is written (Bamidbar 29:17) "who will go out before them and who will come in before them, and who will take them out and who will bring them back. And let the congregation of the L-rd not be as sheep without a shepherd." And this is expounded in the tradition (Song of Songs 1:7) "Tell me, O You whom my soul loves: Where will You graze (Your flock)? Where will you lay (them down) in the afternoon? For why should I be like (a woman) veiled (in mourning) among the flocks of Your neighbors?" What did the Holy One Blessed be He answer? (Ibid. 8) "If you do not know, O fairest of the women (i.e., "greatest of the prophets"), go out in the footsteps of the sheep" (i.e.,) what I am destined to do with them in the future. Israel passed through four exiles — without a shepherd, without a prophet, without a sage. And thus is it written of the days of Achav (II Chronicles 18:16) "I have seen all of Israel scattered on the mountains like sheep that have no shepherd."