Sayyiduna Abdullah bin Amr (may Allah be pleased with him) reports this saying of the Prophet (peace and blessings be upon him): "In Paradise there are chambers whose outside can be seen from the inside and whose inside can be seen from the outside." Sayyiduna Abu Malik al-Ash'ari (may Allah be pleased with him) said: "O Messenger of Allah! For whom will they be?" the Prophet (peace and blessings be upon him) said: "For the one who speaks good words, feeds others, and spends the night standing (that is, offering voluntary prayers) while people are asleep."
Ahmad and al-Tabarani in al-Mu'jam al-Kabir recorded it, and its chain is hasan (good); the wording is his (al-Tabarani's). In Ahmad's narration the words are: "Sayyiduna Abu Musa al-Ash'ari (may Allah be pleased with him) asked."