This Amazing Spider-Man #33 from February 1966 by Stan Lee and Steve Ditko. The Final Chapter!
Wow! I mean just Wow!
I know exactly where I got this issue - eBay, and I know why I got it. In 2007 Jonathan Ross made a TV documentary called In search of Steve Ditko in which he recounted his own childhood love for Ditko's comic books. Ross and Neil Gaiman travelled to New York to track down the notoriously reclusive Ditko, they find him but he declines their request for an on-camera interview. It's well known that many of the early Spider-Man stories were plotted by Ditko with Stan Lee providing ideas and then adding dialogue to Ditko's pages. In the documentary Gaiman describes this particular issue and suggests it is one of the top five greatest super-hero moments, maybe even the greatest.
When he was discussing this story I was taken back to when I read it in the black and white Marvel UK reprints in the 1970s. Next thing I knew I was bidding for an issue on eBay and here it is. The story in a nutshell is that Aunt May is sick and only a special serum can save her if Spider-Man can get it to Dr Curt Connors in time. But Doctor Octopus has the serum in his underwater lair and as this issue begins Spidey has been trapped under a huge piece of machinery while the damaged roof begins to leak and the serum lies just out of reach. The situation is grim and Spider-Man is on the point of giving up. However he finds hidden strength and overcomes adversity in a series of gripping Ditko panels that culminate in a glorious full page image of triumph. To be honest it doesn't really need the Stan the Man Lee word bubbles. The sequential art speaks for itself. It's a fantastic moment in a fantastic issue.