Sunan an-Nasa'i, Hadith 1870 ⓘ
Abu lyas Mu'awiyah bin 'Qurrah narrated from his father that: a man came to the Prophet accompanied by a son of his. He said to him: "Do you love him?" He said: "May Allah love you as I love him." Then he (the son) died and he noticed his absence and asked about him. He said: "Will it not make you happy to know that you will not come to any of the gates of Paradise but you will find him there, trying to open it for you?"
أَخْبَرَنَا عَمْرُو بْنُ عَلِيٍّ، قَالَ حَدَّثَنَا يَحْيَى، قَالَ حَدَّثَنَا شُعْبَةُ، قَالَ حَدَّثَنَا أَبُو إِيَاسٍ، - وَهُوَ مُعَاوِيَةُ بْنُ قُرَّةَ - عَنْ أَبِيهِ، رضى الله عنه أَنَّ رَجُلاً، أَتَى النَّبِيَّ صلى الله عليه وسلم وَمَعَهُ ابْنٌ لَهُ فَقَالَ لَهُ " أَتُحِبُّهُ " . فَقَالَ أَحَبَّكَ اللَّهُ كَمَا أُحِبُّهُ . فَمَاتَ فَفَقَدَهُ فَسَأَلَ عَنْهُ فَقَالَ " مَا يَسُرُّكَ أَنْ لاَ تَأْتِيَ بَابًا مِنْ أَبْوَابِ الْجَنَّةِ إِلاَّ وَجَدْتَهُ عِنْدَهُ يَسْعَى يَفْتَحُ لَكَ " .
also referenced under: Book 21, Hadith 53 (In-Book) & Volume 3, Book 21, Hadith 1871 (DarusSalam)