《北史·列传·卷十一》
保定三年，让于谨成为朝中的三老之一，于谨坚决辞谢，又不得许可。
三年，以谨为三老，固辞，又不许。
In the third year of Baoding, Yu Jin was made one of the three senior advisors in the court, but he firmly declined, and his request was again not granted.