Praying the Duha prayer is like charity given on behalf of your body

from the Prophet ﷺ that he said: Each morning, charity is due upon every joint of one of you. Every glorification (saying ‘subḥān Allāh’) is charity, every praise (saying ‘al-ḥamdu lillāh’) is charity, every declaration of Allah’s oneness (saying ‘lā ilāha illā Allāh’) is charity, every magnification (saying ‘Allāhu akbar’) is charity; enjoining what is right is charity and forbidding what is wrong is charity. And two rak'ahs of prayer that one performs at the time of ḍuḥā (forenoon) suffice for all of that.

عَنِ النَّبِيِّ ﷺ أَنَّهُ قَالَ: «يُصْبِحُ عَلَى كُلِّ سُلاَمَى مِنْ أَحَدِكُمْ صَدَقَةٌ، فَكُلُّ تَسْبِيحَةٍ صَدَقَةٌ، وَكُلُّ تَحْمِيدَةٍ صَدَقَةٌ، وَكُلُّ تَهْلِيلَةٍ صَدَقَةٌ، وَكُلُّ تَكْبِيرَةٍ صَدَقَةٌ، وَأَمْرٌ بِالْمَعْرُوفِ صَدَقَةٌ، وَنَهْىٌ عَنِ الْمُنْكَرِ صَدَقَةٌ، وَيُجْزِئُ مِنْ ذَلِكَ رَكْعَتَانِ يَرْكَعُهُمَا مِنَ الضُّحَى۔»

that he asked 'A'isha ؓ how many rak'ahs Messenger of Allah ﷺ prayed at the forenoon prayer. She replied: Four rak'ahs, but sometimes more as he pleased.

أَنَّهَا سَأَلَتْ عَائِشَةَ ؓ كَمْ كَانَ رَسُولُ اللَّهِ ﷺ يُصَلِّي صَلاَةَ الضُّحَى قَالَتْ أَرْبَعَ رَكَعَاتٍ وَيَزِيدُ مَا شَاءَ

The Messenger of Allah ﷺ used to observe four rak'ahs in the forenoon prayer and he sometimes observed more as Allah pleased.

كَانَ رَسُولُ اللَّهِ ﷺ يُصَلِّي الضُّحَى أَرْبَعًا وَيَزِيدُ مَا شَاءَ اللَّهُ

three fasts during every month, two rak'ahs of the forenoon prayer, and observing Witr prayer before going to bed.

أَوْصَانِي خَلِيلِي ﷺ بِثَلاَثٍ بِصِيَامِ ثَلاَثَةِ أَيَّامٍ مِنْ كُلِّ شَهْرٍ وَرَكْعَتَىِ الضُّحَى وَأَنْ أُوتِرَ قَبْلَ أَنْ أَرْقُدَ