I asked Jabir "Did the Prophet (ﷺ) forbid fasting on Fridays?" He replied, "Yes." (Other narrators added, "If he intends to fast only that day.")
Sahih al-Bukhari Book 30, Hadith 91
← Previous Hadith That the Prophet (ﷺ) asked him (Imran) or asked a man and `Imran was listening, "O Abu so-and-so! Have you fasted the last days of this month?" (The narrator thought that he said, "the month of Ramadan"). The man replied, "No, O Allah's Messenger (ﷺ)!" The Prophet (ﷺ) said to him, "When you finish your fasting (of Ramadan) fast two days (in Shawwal)." Through another series of narrators `Imran said, "The Prophet (ﷺ) said, '(Have you fasted) the last days of Sha'ban?"

Sahih al-Bukhari Book 30, Hadith 90 Next Hadith → I heard the Prophet (ﷺ) saying, "None of you should fast on Friday unless he fasts a day before or after it."

Sahih al-Bukhari Book 30, Hadith 92