the blackest crow

The blackest crow that ever flew 
would surely turn to white
If ever I prove false to you 
bright day be turned to night
Bright day will turn to night my love 
the elements will mourn
If ever I prove false to you 
the seas will rage and burn.

And when you’re on some foreign shore
think of your absent friend
And when the wind blows high and clear 
a line to me pray send
And when the wind blows high and clear 
pray send your love to me
That I might know by your sweet hand 
our time has gone with thee

A very old song - the tune appears in the Appalachians and the Ozarks around the time of the American Civil War.  The lyrics may be much older.

The sentiments though, still speak to us, with so many people facing separation from their loved ones.