Are there sourcers that show the importance of hard work according to the Torah or Halacha etc.? Working hard, in general, is an important concept but are there mekoros for it?

See at length, many tens of sources in the second positive character trait in Mesilat Yesharim, "Zrizut", where there are 4 entire (!) chapters (ch. 6-9) there exactly on the topic of being energetic, having zeal, working hard, not to be lazy etc. etc. The Ramchal cites there sources from the Torah like by Ya'akov who worked diligently and honestly for Lavan (31, 40), and especially many psukim from Mishlei e.g. 6, 6-10; 18, 9; 24, 30, etc. In fact, one of the basic commandments to Adam upon his creation, was to "work" Gan Eden (and even his punishment, that his toil will be difficult, is an educational one, as are all of God's punishments). Lehavdil, the Protestants, because they don't perform the mitzvot, focused on that Jewish "Work Ethic" as even one of the central themes of religion, but they clearly learned it from us! All of this is multiplied that much more when one is working for others, where if he doesn't work hard, it's an issue of stealing from the boss, who is paying your salary. But as above, we see that it's actually a positive Torah ideal, and especially, in Eretz Yisrael where work is the mitzvah of settling the Land of Israel.