Mishkat al-Masabih 30 Fine Qualities كتاب المناقب 300

وَعَنْ أَبِي أُمَامَةَ أَنَّ رَسُولَ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ قَالَ: «طُوبَى لِمَنْ رَآنِي [وَآمَنَ بِي] وَطُوبَى لِمَنْ لَمْ يَرَنِي وَآمَنَ بِي» . رَوَاهُ أَحْمد

Abu Umama reported God’s messenger as saying, “Blessed is he who has seen me, but seven times blessed is he who has not seen me but has believed on me.” Ahmad transmitted it.