《资治通鉴·梁纪·梁纪十四》
给事黄门侍郎杨说道： 养狗就是为了让它叫，现在要是因为一条狗叫了几声便杀掉它，恐怕将来再也没有能叫的狗了。 
给事黄门侍郎杨愔曰： 畜狗求吠；今以数吠杀之，恐将来无复吠狗。 
The Official on Duty, Palace Attendant Yang said: One keeps a dog because one wants it to bark; now, if one were to kill a dog because it barked a few times, I fear that in future there would be no more dogs that would bark.