The reason the Prophet refrained from maintaining the Duha prayer

The questioner : Yes. The issue here is that the Prophet (peace and blessings be upon him) refrained from maintaining the Duha prayer for fear that the community would consider it obligatory, even though there are other recommended practices (sunnah) that he maintained, such as the regular voluntary prayers (rawatib) before Fajr and standing in night prayer.

The Shaykh : Yes, because these are attached to the obligatory prayers. Regarding the night prayer, Allah commanded him explicitly: "Stand in prayer during the night, except for a little." He could not abandon it, for Allah had commanded him to do so.