The Dhammapada - 15 &16

He grieves here, he grieves after death,

in both states does the wrongdoer grieve. 

He grieves, he is vexed, having seen his own evil deeds.

 Doing evil deeds is a sure way to grief and despair. As we know from modern history, the greatest evildoers of this century (Stalin, Mao, Hitler, etc.) did not have an easy life. Their were troubled personalities, seeing enemies behind every shadow. The amount of evil they created hunted them mercilessly and efficiently.

If we commit an evil deed (a definition of evil deed is that it is an action which harms other living beings in any way -- physical or mental) not only our consciences bothers us (or at least it should, if we are to call ourselves human beings), but it will also bring us a bad rebirth. Thus, when we see our evil deeds, we will grieve both in this life and in the next one.

He rejoices here, he rejoices after death, 

in both states does the well-doer rejoice. 

He rejoices, he is happy, having seen his own good deeds.

In direct contrast to the verse 15 (see), if we commit good deeds, helping all living beings in different ways, we will not only be happy in this life, having the satisfaction of doing good deeds, but we will also obtain a favorable rebirth. So, when we see our good deeds, we rejoice in the knowledge thereof.