"Okay, it's our favourite part", Nuefelder told her in the gut-wrenching video, which has since been shared widely on social media.
Olivia composed on Facebook: "Miss Marg has touched my heart in such an unbelievable way".
"I am so humbled and honoured to be a Nurse. My thoughts and prayers are forever with this wonderful family", Neufelder said in a Facebook post.
The video was posted on Facebook early Tuesday by Smith's daughter Megan Smith, and has been liked by 3.4 million viewers as of Friday morning. A video showing a cancer patient being serenaded by her sweet nurse shortly before she left this earth is going viral.
"Words can't depict the thankfulness and love we feel for nurture Olivia who mother calls her blessed messenger!"
'Your dedication to your patients is beyond any that I have seen, you truly are a beam of light and I can not thank you enough for the compassion and care and love you shared for my mother. "God bless you Olivia".
The patient in question, 63-year-old Margaret Smith, was taken to the facility because her health began to decline, according to Fox 59.
As you can see, nurse Neufelder is overwhelmed by emotion a couple of times, but she still urges Smith to smile and join in the song with her.
Smith said not only did Nuefelder sing to her mom, she also sat with her until her anesthesia wore off. She had been suffering from liver cancer for about a year.
"I'll bet it's so nice up in heaven since you arrived".