From Su Shi's 《前赤壁赋》 (Former Red Cliffs Rhapsody): 取之无禁,用之不竭 — 'there is no prohibition against taking it, and it is inexhaustible in use,' referring to the river breeze and mountain moon.
usage
Almost always paired with 取之不尽 (qǔ zhī bù jìn) as 取之不尽,用之不竭. Used for natural resources, knowledge, inspiration — rarely for finite items.