https://torontodawah.com/the-ruling-on-fasting-the-six-days-of-shawwal-before-making-up-the-missed-days-from-ramadaan-shaykh-bin-baz-shaykh-muhammad-nasiruddin-al-albani-and-shaykh-ibn-uthaymeen/
The Ruling On Fasting The Six Days Of Shawwal Before Making Up The Missed Days From Ramadaan - Shaykh Bin Baz, Shaykh Muhammad Nasiruddin Al-Albani, And Shaykh Ibn Uthaymeen