"Mamas Don't Let Your Babies Grow Up to be Cowboys" was written by Ed and Patsy Bruce. It was made famous by Waylon Jennings and Willie Nelson.
Here's the first verse and chorus of the song:
Cowboys ain't easy to love and they're harder to hold.
They'd rather give you a song than diamonds or gold.
Lonestar belt buckles and old faded levis,
And each night begins a new day.
If you don't understand him, an' he don't die young,
He'll prob'ly just ride away.
Mamas, don't let your babies grow up to be cowboys.
Don't let 'em pick guitars or drive them old trucks.
Let 'em be doctors and lawyers and such.
Mamas don't let your babies grow up to be cowboys.
'Cos they'll never stay home and they're always alone.
Even with someone they love.
Here's an audio link for the song.