Sayyiduna Abu Amrah al-Ansari (may Allah be pleased with him) said: I know this only from the Messenger of Allah (peace and blessings be upon him): that he (peace and blessings be upon him) was asked: O Messenger of Allah! What do you say about the one who believed in you but did not see you, and affirmed you but did not see you - what is there for them? He (peace and blessings be upon him) said: "Glad tidings for them, glad tidings for them. They are of us; they are with us."
Hadith Referenceالمعجم الكبير للطبراني / باب الألف / 572