It is recommended to pray Duha, the least of which is two rak`ah, the best of which is eight, and the average of which is four or six, and encouragement to do so regularly
وَحَدَّثَنَا عُبَيْدُ اللَّهِ بْنُ مُعَاذٍ، حَدَّثَنَا أَبِي، حَدَّثَنَا كَهْمَسُ بْنُ الْحَسَنِ الْقَيْسِيُّ، عَنْ عَبْدِ اللَّهِ بْنِ شَقِيقٍ، قَالَ قُلْتُ لِعَائِشَةَ أَكَانَ النَّبِيُّ صلى الله عليه وسلم يُصَلِّي الضُّحَى قَالَتْ لاَ إِلاَّ أَنْ يَجِيءَ مِنْ مَغِيبِهِ
'Abdullah b. Shaqiq reported: I aksed 'A'isha whether the Messenger of Allah (ﷺ) used to observe the forenoon prayer. She said: No, except when he came back from a journey.