Hadith #2432 (Sunan Abi Dawud)
Book: Fasting (Kitab Al-Siyam)
Narrator(s): Abdul 'Aziz bin Muhammad al-Daruradi عبد العزيز بن محمد الدراوردي, Abu Ja'far al-Nafaili عبد الله بن محمد أبو جعفر النفيلي الحران, Safwan bin Slym al-Madni صفوان بن سليم المدني أبو عبد الله, Umar bin Thabit عمر بن ثابت الأنصاري
Grade: Da'if

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.

Source: https://parallelquran.com/hadith/sunan-abi-dawud-2432/