It is narrated from Hazrat Aisha (may Allah be pleased with her) that the Prophet (peace and blessings be upon him) never performed the Duha prayer. Sometimes, despite loving a certain act, the Prophet (peace and blessings be upon him) would abandon it only because he feared that people might start practicing it regularly, and as a result, it might become obligatory upon them (and then they might not be able to perform it). Therefore, the Prophet (peace and blessings be upon him) preferred that there should be more ease in the obligations upon the people.