Midrasz do Amosa 5:2

R. Jochanan said: "Why is the letter Nun missing in the [alphabetical course of] Ashrei? Because the letter Nun is used for bad tidings. It is said (Amos 5, 2.) She is fallen (Nafla) and will not rise again, the virgin of Israel." In Palestine they interpret [this prophecy of Amos as good tidings] thus: She is fallen and will not fall again! Rise! virgin of Israel! R. Nachman b. Isaac said: "Even so, David indicates [the prophecy of] the Nun for the purpose of strengthening Israel, through a holy vision; for he says (Ps. 145, 14.) The Lord upholdeth all who are fallen (Noflim)."

R. Elazar b. Abina said : "He who recites Te-hila l' David (Ps. 145) three times a day may be sure of an inheritance in the world to come." What is the reason? Shall I say because that particular chapter is arranged alphabetically? Then why not prefer chapter 119 Ps., which has an arrangement of eight repetitions of each letter of the alphabet? Is it because it has the verse Thou openeth Thy hand and satisfieth the demands of all Thy creatures. [it influences men to be benevolent] ? If so, then why not the Great Hallel? in which also is written (Ib. 136, 25.) He giveth food to all flesh. Because Tehila l' David has the advantages of both; [is arranged alphabetically and influences men to be benevolent] R. Jochanan said : "Why is the letter Nun missing in the [alphabetical course of] Ashrei? Because the letter Nun is used for bad tidings. It is said (Amos 5:2) She is fallen (Nafla) and will not rise again, the virgin of Israel." In Palestine they interpret [this prophecy of Amos as good tidings] thus: She is fallen and will not fall again! Rise! virgin of Israel! R. Nachman b. Isaac said: "Even so, David indicates [the prophecy of] the Nun for the purpose of strengthening Israel, through a holy vision; for he says (Ps. 145:14) The Lord upholdeth all who are fallen (Noflim)."