I thought it was another song Johannes Brahms wrote for Clara Schumann.
In fact, Brahms had it dedicated to one of his former lover:
The cradle song was dedicated to Brahms’s friend, Bertha Faber, on the occasion of the birth of her second son. Brahms had been in love with her in her youth and constructed the melody of the “Wiegenlied” to suggest, as a hidden counter-melody, a song she used to sing to him.
Wikipedia
Does that matter? Btw, here’s a version that feels like the kids’ having a party sleepover: