《隋书·列传·卷二十八》
当时义臣还年幼，养育在宫中。不满二十岁，就已奉诏像千牛那样当侍卫几年了，皇上给他的赏赐很多。
时义臣尚幼，养于宫中，年未弱冠，奉诏宿卫如千牛者数年，赏赐甚厚。
At that time, Yichen was still young, and he was being nursed in the palace. He was less than twenty years old, but several years he had served as an attendant, like Qianniu, as ordered by the imperial edict, and the emperor greatly rewarded him.