Our Master, Rabbi Yosef Karo of blessed memory, wrote that it is good to say the passage of the Manna in order to strengthen our belief that our entire livelihood, down to the tiniest detail, comes through Hashem's providence. Rabenu Bahֻya mentions a tradition handed down by our sages that anyone who says the passage of the Manna is promised that he will never lack sustenance. The author of Yesh Nohֻlin states, I found in the writings of the Kabbalists that one should say each verse twice followed by the Targum Onkelos. Rabbi hֻayim Palazzi and his son Rabbi Yitshֻak concur and add that the Shevet Mussar and Kemahֻ Solet concur as well. Indeed, Rabbi hֻayim Vital was accustomed to reading this passage before Shahֻarit until Rabenu HaAri told him to stop. According to the Shaarey Teshuvah, Rabbi Yaakov Emdin, and Kaf Hahֻayim, it appears that the Ari was against reading it before the prayers but would agree that doing so after the prayers are permitted.