《北史·列传·卷十一》
待破六韩拔陵为首在北境叛乱时，援引蠕蠕作为后援，大行台元纂领兵讨伐，他一向听说于谨的名声，便请他当铠曹参军事，随军北伐。
及破六韩拔陵首乱北境，引蠕蠕为授，大行台元纂讨之。夙闻谨名，辟为铠曹参军事，从军北伐。
When Liu Ling, the leader of the Northern Qi, rebelled in the north, relying on Rouran as backup, the Grand General Yuan Zuan led troops to suppress the rebellion. He had heard of Yu Jin’s reputation and invited him to serve as the military consultant of the armor department, and to join the northern expedition.