Ba'al Shem Tov, Ki Tavo 6/בעל שם טוב על התורה·כי תבוא ו׳

1Because you did not serve the L‑rd your G‑d in joy, and with gladness of heart, for the abundance of all things. (Ibid. 28:47)When the leaders of the generation are happy, they arouse joy in the entire world.Dibras Shlomo, Shemini