What is the ruling on one who abandons the Duha prayer for fear of showing off after being visited by someone?

A supererogatory prayer (nafilah) should not be interrupted except for a legitimate Shar'i reason, and the entrance of a person while one is praying is not a legitimate reason to interrupt it. If it is interrupted for fear of being thought ostentatious, then this itself is ostentation (riya'); because abandoning an action for the sake of people is ostentation. However, if abandoning an action is out of fear of falling into ostentation, it may be permissible in some cases, but interrupting the prayer for this reason might be a deception from Satan. One should strive for sincerity instead of interrupting the prayer.