Sunan an-Nasa'i, Book 1, Hadith 270 (In-Book) ⓘ
It was narrated from Huthaifah that the Prophet met him when he was Junub: "And he came close to me and reached out his hand. I said: 'I am Junub.' He said: 'The Muslim is not made impure (Najis).'"
أَخْبَرَنَا إِسْحَاقُ بْنُ مَنْصُورٍ، قَالَ أَخْبَرَنَا يَحْيَى، قَالَ حَدَّثَنَا مِسْعَرٌ، قَالَ حَدَّثَنِي وَاصِلٌ، عَنْ أَبِي وَائِلٍ، عَنْ حُذَيْفَةَ، أَنَّ النَّبِيَّ صلى الله عليه وسلم لَقِيَهُ وَهُوَ جُنُبٌ . فَأَهْوَى إِلَىَّ فَقُلْتُ إِنِّي جُنُبٌ فَقَالَ " إِنَّ الْمُسْلِمَ لاَ يَنْجُسُ " .
also referenced under: Volume 1, Book 1, Hadith 269 (DarusSalam)