Sahih Muslim
The Book Pertaining to Paradise, Its Description, Its Bounties and Its Intimates (Kitab Al-Jannat wa Sifat Naimiha wa Ahliha)
Book Number: 040 / Hadith Number: 6790
Abu Sa'id al-Khudri reported Allah's Messenger (may peace be upon him) as saying: The inmates of Paradise would see the inmates of the apartment over them just as you see the shining planets which remain in the eastern and the western horizon because of the superiority some have over others. They said: Allah's Messenger, would in these abodes of Apostles others besides them not be able to reach? He said: Yes, they will, by Him, in Whose hand is my life, those who believe in God and acknowledge the Truth, will reach them.