不孝有三

Recent topic on mitbbs, also from Baidu knows:

"""
不孝有三，无后为大

“不孝有三，无后为大”出自《孟子·离娄上》。原文是：“不孝有三，无后为大，舜不告而娶，为无后也，君子以为犹告也”。 《十三经注疏》中在“无后为大”下面有注云：“于礼有不孝者三，事谓阿意曲从，陷亲不义，一不孝也；家贫亲老，不为禄仕，二不孝也；不娶无子，绝先祖祀， 三不孝也。三者之中无后为大。” 白话问解释就是：一味顺从，见父母有过错而不劝说，使他们陷入不义之中，这是第一种不孝；家境贫穷，父母年老，自己却不去当官吃俸禄来供养父母，这是第二 种不孝；不娶妻生子，断绝后代，这是第三种不孝 。
"""

It is interesting to note that although 无后为大 is known as the most important trespass against one's parents, the foremost to be mentioned is the error of "阿意曲从，陷亲不义", and secondly "家贫亲老，不为禄仕". Both very practically important. Statistically, #1 and #2 are probably more frequent and causes #3.