question #1 Sahih Muslim 198b, Book 1, Hadith 394 : What is the significance of the reserved prayer of the Prophet for his Ummah on the Day of Resurrection?

The Messenger of Allah (ﷺ) said: There is for every apostle a prayer, and I intend (if Allah so willed) that I would reserve my prayer for the intercession of my Ummah on the Day of Resurrection.