Sayyiduna Abu Musa al-Ash'ari (may Allah be pleased with him) narrates that the Prophet (peace and blessings be upon him) said: "Whoever offers four rak'ahs at the time of Duha and offers four rak'ahs before Zuhr, a house is built for him in Paradise."
Al-Tabarani recorded it in al-Mu'jam al-Awsat and al-Mu'jam al-Kabir; its chain contains a group of narrators who are not known.