Sayyiduna Abu Musa al-Ash'ari (may Allah be pleased with him) narrates that the Prophet (peace and blessings be upon him) said: "Whoever prays the Duha (forenoon) prayer, and prays four rak'ahs before Duha, a house is built for him in Paradise."
Al-Tabarani recorded it in al-Mu'jam al-Kabir; its chain contains a group of narrators about whom I have not seen anyone give an account.