《资治通鉴·唐纪·唐纪七十六》
李克用有时错怪迁怒于手下将吏，盖寓必定表面上为李克用助威加油，结果往往使李克用消去怒气。盖寓劝说李克用改正过错时，必定拿近前的一些事作比喻。因此李克用对盖寓宠爱信任，所辖境内的将领官吏也无不依附盖寓，他的权力几乎与李克用等同。
克用或以非罪怒将吏，寓必阳助之怒，克用常释之；有所谏诤，必征近事为喻；由是克用爱信之，境内无不依附，权与克用侔。
At times, Li Keyong would mistakenly blame and punish his generals. When this happened, Gai Yu would outwardly express his support for Li Keyong's actions. As a result, Li's anger would usually subside. When Gai Yu advised Li Keyong to correct his mistakes, he would always use examples from recent events. Because of this, Li Keyong became fond of and trusted Gai, and all of the generals and officials of the territory under his jurisdiction were also dependent on Gai. His authority was nearly equal to Li Keyong's.