Fortunately, he explained in 2005:
“I heard a couple arguing about money. She was saying she needed money and he was saying the work he was doing was not giving him enough. I relate to those things and began to sing a little song – ‘You get up in the morning and you slaving for bread.’ By the time I got home, it was complete.”
I assume the song is tied to the Rastafarians and is related to their claim to be a lost tribe of Israel, thus the title.
The single was among the first ska tunes to reach the US top ten. “In June 1969 it peaked at #9 on the [US] Billboard Hot 100 singles chart. It hit number one in the United Kingdom [the first ska number to do so], Netherlands, Jamaica, South Africa, Canada, Sweden and West Germany.”