Abu al-Aswad al-Dailani said:
While we were present with Abu Dharr, he said: In the morning, alms are due for him, ever fast is alms, every pilgrimage is alms, every utterance of "Glory to be Allah" is alms, every utterance of "Allah is most great" is alms, every utterance of "Praise be to Allah" is alms. The Messenger of Allah ﷺ recounted all such good works. He then said: Two rak'ahs which one prays in the Duha serve instead of that.

حَدَّثَنَا وَهْبُ بْنُ بَقِيَّةَ، أَخْبَرَنَا خَالِدٌ، عَنْ وَاصِلٍ، عَنْ يَحْيَى بْنِ عُقَيْلٍ، عَنْ يَحْيَى بْنِ يَعْمُرَ، عَنْ أَبِي الأَسْوَدِ الدُّؤَلِيِّ، قَالَ بَيْنَمَا نَحْنُ عِنْدَ أَبِي ذَرٍّ قَالَ " يُصْبِحُ عَلَى كُلِّ سُلاَمَى مِنْ أَحَدِكُمْ فِي كُلِّ يَوْمٍ صَدَقَةٌ فَلَهُ بِكُلِّ صَلاَةٍ صَدَقَةٌ وَصِيَامٍ صَدَقَةٌ وَحَجٍّ صَدَقَةٌ وَتَسْبِيحٍ صَدَقَةٌ وَتَكْبِيرٍ صَدَقَةٌ وَتَحْمِيدٍ صَدَقَةٌ " . فَعَدَّ رَسُولُ اللَّهِ ﷺ مِنْ هَذِهِ الأَعْمَالِ الصَّالِحَةِ ثُمَّ قَالَ " يُجْزِئُ أَحَدَكُمْ مِنْ ذَلِكَ رَكْعَتَا الضُّحَى " .