I asked 'Aishah: Would the Messenger of Allah ﷺ fast three days every month ? She replied: Yes. I asked: Which days in the month he used to fast ? She replied: He did not care which days of the month he fasted. (Using translation from Abū Dāʾūd 2453)
عَائِشَةَ ؓ أَكَانَ رَسُولُ اللهِ ﷺ يَصُومُ مِنْ كُلِّ شَهْرٍ ثَلَاثَةَ أَيَّامٍ؟ قَالَتْ نَعَمْ قُلْتُ مِنْ أِيِّ أَيَّامِ الشَّهْرِ كَانَ يَصُومُ؟ قَالَتْ مَا كَانَ يُبَالِي مِنْ أِيِّ الشَّهْرِ كَانَ يَصُومُ
Yes I said to her: Which were (the particular) days of the month on which he observed fast? She said: He was not particular about the days of the month on which to observe fast.
أَنَّهَا سَأَلَتْ عَائِشَةَ زَوْجَ النَّبِيِّ ﷺ أَكَانَ رَسُولُ اللَّهِ ﷺ يَصُومُ مِنْ كُلِّ شَهْرٍ ثَلاَثَةَ أَيَّامٍ قَالَتْ نَعَمْ فَقُلْتُ لَهَا مِنْ أَىِّ أَيَّامِ الشَّهْرِ كَانَ يَصُومُ قَالَتْ لَمْ يَكُنْ يُبَالِي مِنْ أَىِّ أَيَّامِ الشَّهْرِ يَصُومُ
I asked 'Aishah: Would the Messenger of Allah ﷺ fast three days every month ? She replied: Yes. I asked: Which days in the month he used to fast ? She replied: He did not care which days of the month he fasted.
قُلْتُ لِعَائِشَةَ أَكَانَ رَسُولُ اللَّهِ ﷺ يَصُومُ مِنْ كُلِّ شَهْرٍ ثَلاَثَةَ أَيَّامٍ قَالَتْ نَعَمْ قُلْتُ مِنْ أَىِّ شَهْرٍ كَانَ يَصُومُ قَالَتْ مَا كَانَ يُبَالِي مِنْ أَىِّ أَيَّامِ الشَّهْرِ كَانَ يَصُومُ