The Hour of Resurrection is named so because it occurs in the last hour of the hours of this world. Or because it happens suddenly and unexpectedly. Just as you say: 'in an hour' to someone you are hurrying. It has become a term for it, like the star for the Pleiades, and the planet for Venus. They intended: their duration in this world, or in the graves, or in what is between the end of this world and the resurrection. In the hadith: 'What is between the two blowings [of the trumpet] is forty.' [[I did not find it like this. In the two Sahihs from Abu Huraira, it is reported that he said: 'What is between the two blowings is forty.' They asked: 'O Abu Huraira, is it forty years?' He said: 'I do not know.' They said: 'Is it forty months?' He said: 'I do not know.' They said: 'Is it forty days?' He said: 'I do not know.']] They said: 'We do not know if it is forty years or forty thousand years?' That is a time in which they perish and their punishment ceases. They only estimate their duration in that way to express their desire for it to be shorter. Or they forget or lie or conjecture. Just as they were turned away from the truth in this world, so they built their matter on what contradicts the truth. Or just as they were turned away, they were deceived by what has now become clear to them, that it was nothing but an hour.