The Messenger of Allah ﷺ said, "Every prophet has a supplication that is granted, and every prophet hastened to make his. But I have reserved my supplication as intercession for my nation on the Day of Resurrection. It will reach, Allah willing, anyone of my nation who dies without associating anything with Allah."
قال رسول الله ﷺ: لكل نبي دعوة مستجابة، فتعجل كل نبي، دعوته، وإني اختبأت دعوتي شفاعة شفاعة لأمتي يوم القيامة، فهي نائلة إن شاء الله من مات من أمتي لا يشرك بالله شيئا.
Muslim narrated it in the Book of Faith (199) through several routes from Abu Muawiya, from Amash, from Abu Salih, from Abu Hurairah, as mentioned.In another narration, through a different route, from Abu Zura, from Abu Hurairah, with the wording, "Every prophet has a prayer that is answered, which he prays and it is granted to him. I have saved up my prayer as intercession for my nation on the Day of Resurrection."