Sayyiduna Abu Hurayrah (may Allah be pleased with him) narrates that the Prophet (peace and blessings be upon him) said: "None will regularly observe the Duha prayer except an 'awwab' (i.e. one who turns to Allah Almighty frequently with repentance; according to one view it means an obedient person)."
Al-Tabarani recorded it in al-Mu'jam al-Awsat; its chain contains Muhammad bin Amr, about whom there is criticism, and its chain also contains a narrator whom I do not know.