"I asked the Messenger of Allah about fasting and he said: 'Fast one day of the month.' I said: 'Fast one day of the month.' I said: 'O Messenger of Allah, let me do more, let me do more.' He said: 'Let me do more, let mo do more; I am able for it.' Then the Messenger of Allah fell silent until I thought that he was going to refuse my request. Then he said: 'fast three days of each month."' (Using translation from Nasāʾī 2433)
سَأَلْتُ رَسُولَ اللهِ ﷺ عَنِ الصَّوْمِ فَقَالَ «صُمْ يَوْمًا مِنَ الشَّهْرِ» قُلْتُ يَا رَسُولَ اللهِ زِدْنِي قَالَ يَقُولُ رَسُولُ اللهِ ﷺ «زِدْنِي زِدْنِي صُمْ يَوْمَيْنِ مِنْ كُلِّ شَهْرٍ» قُلْتُ يَا رَسُولَ اللهِ إِنِّي أَجِدُنِي قَوِيًّا فَقَالَ رَسُولُ اللهِ ﷺ «زِدْنِي زِدْنِي إِنِّي أَجِدُنِي قَوِيًّا» فَسَكَتَ رَسُولُ اللهِ ﷺ حَتَّى ظَنَنْتُ أَنَّهُ لَنْ يَزِيدَنِي قَالَ «صُمْ ثَلَاثَةَ أَيَّامٍ مِنْ كُلِّ شَهْرٍ»