Sayyiduna Abdullah bin Mas'ud (may Allah be pleased with him) said: "Beware of bearing witness (that someone is in Paradise). But if you must do it, then bear witness for the detachment that the Messenger of Allah (peace and blessings be upon him) sent out and that was martyred. Concerning them this message was revealed: Convey to our people from us that we have met our Lord, and He is pleased with us and has made us pleased."
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 10256