Sahih Bukhari - Book of Fasting

Volume 3, Book 31, Number 206:

Narrated Abu Huraira:
I heard the Prophet saying, "None of you should fast on Friday unless he fasts a day before or after it."

Volume 3, Book 31, Number 205:

Narrated Muhammad bin 'Abbas:
I asked Jabir "Did the Prophet forbid fasting on Fridays?" He replied, "Yes." (Other narrators added, "If he intends to fast only that day.")

Volume 3, Book 31, Number 207:

Narrated Abu Aiyub from Juwairiya bint Al-Harith:
The Prophet visited her (Juwairiya) on a Friday and she was fasting. He asked her, "Did you fast yesterday?" She said, "No." He said, "Do you intend to fast tomorrow?" She said, "No." He said, "Then break your fast." Through another series of narrators, Abu Aiyub is reported to have said, "He ordered her and she broke her fast."