This is based on opinion. Please don't list it on a work's trope example list.
Tear Jerker / The Jazz Singer
Say what you will about blackface, but the heart with which Jolson delivers his numbers resonates even today. Of course, the love he has for his mother Sara is so high it starts to become Narm, but regardless...
Every rendition of "Kol Nidre," most especially Jolson finally singing it at the end with perhaps his most heartfelt voice throughout the picture. He sings it when Sara surmises that doing so might bring to pass a miracle, which will rouse him from his deathly illness. When the father hears it, he perks up, acknowledges that his son has earned forgiveness...then dies on the spot, leaving Sara in tears. Then his spirit materializes behind his son, thus signaling the atonement as the hymn comes to a wailing conclusion.