The Book of Virtue, Enjoining Good Manners, and Joining of the Ties of Kinship
حَدَّثَنَا يَحْيَى بْنُ حَبِيبٍ الْحَارِثِيُّ، حَدَّثَنَا يَزِيدُ بْنُ زُرَيْعٍ، حَدَّثَنَا خَالِدٌ، عَنْ أَبِي قِلاَبَةَ، عَنْ أَبِي أَسْمَاءَ الرَّحَبِيِّ، عَنْ ثَوْبَانَ، عَنِ النَّبِيِّ صلى الله عليه وسلم قَالَ " إِنَّ الْمُسْلِمَ إِذَا عَادَ أَخَاهُ الْمُسْلِمَ لَمْ يَزَلْ فِي خُرْفَةِ الْجَنَّةِ حَتَّى يَرْجِعَ " .Thauban reported Allah's Apostle (ﷺ) as saying:Verily, when a Muslim visits his brother in Islam he is supposed to remain in the fruit garden of Paradise until he returns
From Sahih Muslim, whose reports the scholars accept as authentic.