Sayyiduna Abu Malik al-Ash'ari (may Allah be pleased with him) narrates that the Prophet (peace and blessings be upon him) said: "In Paradise there are chambers whose inside can be seen from the outside and whose outside can be seen from the inside. Allah Almighty has prepared them for those (that is, for the one) who feeds others, speaks gently, fasts continuously, and offers voluntary prayers at night while people are asleep."
Al-Tabarani recorded it in al-Mu'jam al-Kabir, and its narrators are thiqat (trustworthy).