What's a good song to sing when someone is leaving but you know you'll see him/her again?

My brother just got into the Peace Core. He's going to some where in
South Africa to teach English at the Peace Core. He's going to France
in July to learn some French first before he leaves in late August or
Mid September so he can communicate better with the people in his
area.

He's going to be gone for 2 years to 3 months.

What's a good song to sing to a family member like this when they're
going away for a certain period of time, but you know you'll see
him/her again.