Rabbeinu Yonah (Sefer HaYira 133) After Torah Study he should go to his business, for it is good to earn a living: no one can serve the Creator if he is busy begging for his meals. And thus said King David: "Happy is everyone who fears the LORD; who walks in his ways. For you shall eat the labor of your hands." (Tehillim 128:1-2).
Rabbeinu Yonah (Avos 02:03)Torah Study is good when combined with derech eretz. In this case it means working for a living. Sometimes derech Eretz is taken literally and sometimes it refers to working for a living it depends on context.
Rabbeinu Yonah (Avos 2:02) And all study of the Torah in the absence of a worldly occupation comes to nothing in the end: Like the matter that they said in our treatise (Avot 3 17), "If there is no flour, there is no Torah." The matter is like its simple understanding - when he neglects work, it brings him to poverty and it drags along several sins and its evil is great. As on account of it, he will 'love gifts and not live,' and flatter people even if they are evildoers, in order that they give to him. Also when the money from the gifts runs out, he will become a thief or a kidnapper (or gambler) and will bring 'home loot taken from the poor' so that he not die of hunger. And when a person reaches these traits, his spirit knows no restraint and he will not rest and not be still until he transgresses all of the commandments that are stated in the Torah, since 'one sin brings along another sin.'