Someone has done anything bad, so he gets something bad back, someday. If someone has done what good, he or she will also get back something good!
In English we say (as Justim Timberlake said it): What goes around, comes around.
Can you translate this in Spanish as:
"Todo lo que sube tiene que bajar" ?
I am not sure because I've read that this sentence is technically meant.
(As for example, the gravity.)