Midrasch zu Schemuel II 10:12

R. Simlai expounded: "A man should always arrange the praises of the Holy One, praised be He! and then pray for what he needs. Whence do we derive this? From Moses; for it is written (Deu. 3, 23.) And I besought the Lord at that time. And it is written also (Ib.) Thou hast begun to show Thy servant thy greatness, and Thy mighty hand; for what God is there in the heavens or on earth that can do aright like Thy works, and like Thy mighty deeds? And following this it is written Let me go over, I pray Thee, that I may see the good land, etc."