The Companion of the Prophet (peace be upon him), Anas (may Allah be pleased with him) said:
We were sitting in the presence of Allah’s Messenger (sallallaahu `alayhi wa sallaam) one day, and he said: “A person is about to arrive from this mountain path who is from the people of Paradise.”
So a person from the Ansaar (a Medinan who helped the Prophet (peace be upon upon) when he migrated to Madinah) arrived, his beard dripping with water from Wudhoo' and his left hand carrying his sandals. He greeted us with Salaams.
The second and the third day the Prophet (sallallaahu `alayhi wa sallaam) said similar words and the same man appeared in the same condition.
'Abdullah Bin 'Amr Bin Al-'Aas followed the man sought his permission to stay with him for three days .
Then 'Abdullah spent three nights with this person. But he did not see him stand up for the Night Prayer at all! All he did was, mention Allaah and make Takbeer (i.e., say 'Allaahu-Akbar' (Allaah is the Greatest)) when he turned sides on his bed. He would do this till he stood up for the Fajr prayer.
However,' Abdullah said,
“I never heard him speak anything except good.”
So when the three days were over, 'Abdullah told the man, “O, Servant of Allah! I heard Allah’s Messenger (sallallaahu `alayhi wa sallaam) saying on three occasions, ‘A person is about to arrive who is from the people of Paradise,’ and you arrived on those three occasions.
But I have not seen you perform a great deal of deeds, so what is it that made the Prophet (sallallaahu `alayhi wa sallaam) say that about you?”
“I do not harbor disloyalty to any of the Muslims within me, and neither do I feel jealous for the wealth that Allah has bestowed upon them.”
'Abdullah said, “This is what has (made you special) and it’s something we cannot endure.”
Source: Musnad Ahmad (Hadeeth Hasan).