The Messenger of Allah (may Allah's peace and blessings be upon him) would give up a deed, even though he liked to perform it, for fear that people would follow him and perform it, and it would thus become obligatory for them

‘Ā’ishah (may Allah be pleased with her) relates that the Prophet (may Allah's peace and blessings be upon him) would give up a deed, even though he liked to perform it, for fear that people would follow him and perform it, and it would thus become obligatory for them, and this might prove difficult for them. Then, she says that the Prophet would not perform the Duha prayer, but the scholars took this negation to refer to lack of regular performance; that is the Prophet would offer it sometimes, for its merit, and abandon it at other times lest it might beccome obligatory for people, as she mentions early in the Hadīth.