Gustav Mahler, Symphony No. 4, Movement III. The video is of the last few moments, the full movement is posted on Spotify.
I've said it before: I meet my maker when I play Mahler. This past March we performed Mahler's Fourth Symphony, a piece I wasn't terribly familiar with. Its main theme is heaven, namely a child's perspective of heaven. It weaves through Mahler's complex religiosity, torn between faith and doubt, but ultimately ends on the innocence of a child's view of the unknown.
The third movement of this piece, as our conductor would say, is the emotional center. You can hear Mahler's questioning and pleading with a God he wants to know and be real. In the final minutes, you literally hear the opening of the gates of heaven (4:11). For me, it's the moments shortly after that demonstrates Mahler's mastery. The theory of heaven is that it is so overwhelming, so beautiful that our minds simply cannot comprehend it. At this point in the piece (5:00-end), the image in my mind is that of a soul seeing such beauty for the first time, being at peace and one with their maker. It's such an overwhelming moment that there are still trickles of doubt that you can hear as the movement quietly comes to an end, however it concludes serene and doubtless. Even for someone who does not believe in that ending as a reality I think it is a beautiful thought.