Action Comics #237

For many years wealthy eccentric Henry Furst has been obsessed with exposing Superman's secret identity, hiring experts and quizzing would-be assassins and barbers. When he has a heart attack, Perry sends Clark to cover the story. Clark is requested to come to Furst's bedside, where he honors a dying man's request for confirmation that he is indeed Superman. As he types up the obituary comes the news that Furst has revived (it was a drug-induced trick). So he pre-empts the impending revelation by changing to Superman in front to Lois and Perry.