《史记·七十列传·匈奴列传》
所以他们在急迫之时，就人人练习骑马射箭的本领，在时势宽松的时候，人们都欢乐无事，他们受到的约束很少，容易做到。
故其急则人习骑射，宽则人乐无事，其约束轻，易行也。
So when they are urgent, everyone practices the skills of riding horses and archery. When the situation is easy, people are happy and have nothing to do. They are less constrained and easy to do.