the Messenger of Allah said: "None of you should fast on Friday unless he fasts before it, or he fasts after it."
Jami` at-Tirmidhi Book 8, Hadith 62
← Previous Hadith "The Messenger of Allah would fasting during the beginning of every month for three days, and Friday was the least of the days that he did not fast."

Jami` at-Tirmidhi Book 8, Hadith 61 Next Hadith → the Messenger of Allah said: "Do not fast on Saturday except for what has been made obligatory upon you (by Allah). If one of you does not find but a grape peal or a tree's twig, then let him chew it."

Jami` at-Tirmidhi Book 8, Hadith 63