《黄帝内经·素问·刺齐论》
针刺肉不要伤筋的，是说刺肉太过，就要伤损及筋。
刺肉无伤筋者，过肉中筋也。
The so-called "do not injure the tendons when needling the flesh" means that if the needle is inserted too deeply into the flesh, it will damage the tendons.