Simba tracks down Scar in his cave, informing Scar that he's going to be king of Pride Rock. Scar is not enthused.
Scar attracts Simba's attention to the shadowy place that Mufasa warned Simba against. Using reverse psychology, he basically orders Simba to go there, letting slip that it's a badass elephant graveyard.
Simba "promises" never to visit the elephant graveyard.