[Machine] The Prophet ﷺ would always mention the importance of the Hour until the verse "They ask you, [O Muhammad], about the Hour: when is its arrival?" [Al-A'raf 7:187] was revealed in its entirety.  

أَنَّ النَّبِيَّ ﷺ كَانَ لَا يَزَالُ يَذْكُرُ مِنْ شَأْنِ السَّاعَةِ حَتَّى نَزَلَتْ {يَسْأَلُونَكَ عَنِ السَّاعَةِ أَيَّانَ مُرْسَاهَا} [الأعراف 187] الْآيَةَ كُلَّهَا