Safwan bin Slym al-Madni صفوان بن سليم المدني أبو عبد الله · Fasting (Kitab Al-Siyam)

I asked or someone asked the Prophet (ﷺ) about perpetual fasting. He replied: You have a duty to your family. Fast during Ramadan and the following month, and every Wednesday and Thursday. You will then have observed a perpetual fast.