It is narrated from Sayyiduna Utban that once the Prophet (peace be upon him) performed the Duha prayer, and when he finished by saying salam, we also finished by saying salam. This prayer the Prophet (peace be upon him) had performed in his mosque.
Hadith Referenceمسند احمد / مسند المدنيين رضي الله عنهم اجمعين / 16479