"Schlafe, mein Prinzchen, schlaf' ein" ("Sleep, my little prince, fall asleep") is perhaps the most famous Wiegenlied (German lullaby), dating from the 18th century.
The words are by Friedrich Wilhelm Gotter. For many years, the common view was that the melody was composed by Wolfgang Amadeus Mozart. Attribution for the melody has since shifted to either Bernhard Flies or Johann Friedrich Anton Fleischmann.
References
Schlafe, mein Prinzchen, schlaf' ein Wikipedia(Text) CC BY-SA