Sahih Muslim 197
Sahih Muslim · Book 1: The Book of Faith · Regarding the saying of the Prophet (saws): "I will be the first of the people to intercede concerning Paradise, and I will be the Prophet with the Greatest Number of Followers."
Anas b. Malik reported:
وَحَدَّثَنِي عَمْرٌو النَّاقِدُ ، وَزُهَيْرُ بْنُ حَرْبٍ ، قَالاَ حَدَّثَنَا هَاشِمُ بْنُ الْقَاسِمِ ، حَدَّثَنَا سُلَيْمَانُ بْنُ الْمُغِيرَةِ ، عَنْ ثَابِتٍ ، عَنْ أَنَسِ بْنِ مَالِكٍ ، قَالَ قَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم " آتِي بَابَ الْجَنَّةِ يَوْمَ الْقِيَامَةِ فَأَسْتَفْتِحُ فَيَقُولُ الْخَازِنُ مَنْ أَنْتَ فَأَقُولُ مُحَمَّدٌ . فَيَقُولُ بِكَ أُمِرْتُ لاَ أَفْتَحُ لأَحَدٍ قَبْلَكَ " .
The Messenger of Allah (ﷺ) said: I will come to the gate of Paradise on the Day of Resurrection. and would seek its opening. and the keeper would say: Who art thou? I would say: Muhammad. He would then say: It is for thee that I have been ordered, and not to open it for anyone before thee.