Davies said Rehua delivered the song, which spoke of living in service to others, "like a boss".
"I feel very fortunate to have had Rehua take ownership of this song and not only deliver it like a boss, but add to it the richness and depth of his own character, experience and world view - one that is rooted firmly in kaupapa Māori, te ao Māori, te reo Māori.
"Rehua's expression in and of this song, the passion he and everyone who contributed to this song, for me, is essentially its point," she said.
Rehua burst to attention in 2013 when a video of his cover of Rod Stewart's I Don't Want to Talk About It went viral, having garnered more than two million views since.
Singing was something Rehua was "born into" though, he said.
"I was a child who was taken to [kapa haka] practices by my mum and my dad ... and all I heard was all these Māori people singing and it was quite beautiful singing.
"So I guess you could say I was born into it. And it was just something that rubbed off on me."
He said he enjoyed blending the language of his ancestors with today's beats and melodies but was most proud of the fact the song was sung in Māori.
"Being a proud Māori boy and being brought up in the Māori culture, I'm proud that our song is in te reo Māori and that we're promoting our Māori language so that hopefully, not only the Māori people, but New Zealand as a whole, grow a true appreciation of the language," Rehua said.
His mother, Grace Hiini, said he was a "very humble boy", preferring to "hover under the radar".
But she was grateful that he was asked to take part because the song had a beautiful message.
"Love yourself, love your family, love your culture, love your language and your people will flourish.
"Any platform where our language can be used and seen in a positive light is awesome."
