Death

People find it difficult to accept and often enough they misunderstand but;

It takes a person with a really big heart; one with a generous and selfless heart to say;

"Don't be sad. Don't cry."

Because he meant,
"It is okay now, he/she has gone to a better place called heaven."

Because he thinks more of the person who left than the people left behind. But he understands the people left behind the same way everybody understands too, because he is also a person left behind after all and he considers himself as one of those very same people who were left behind too but consoles himself and also the people around him the same way (because it is good to share), just because he is simply a selfless person.