Musannaf Ibn Abi Shaybah

Hazrat Imran bin Husain says that do not fix any day other than Ramadan on which you consider fasting to be obligatory.

Hazrat Ibn Abbas (may Allah be pleased with them both) considered it disliked to give any particular day a special distinction, or to fast on specific days or in specific months in such a way that it is never abandoned.

Ibrahim says that the predecessors considered it disliked for a person to make something obligatory upon himself which Allah has not made obligatory upon him.

Hazrat Ibn Sirin says: Do not single out Friday for fasting, nor Friday night for worship.

Hazrat Tawus considered it undesirable to specify a particular day or month for fasting.

Ibrahim says that the predecessors considered it disliked to single out Friday for fasting and its night for worship.

Hazrat Aamir and Ibrahim considered it undesirable to specify a particular day and fast on it.

Hazrat Mujahid says that do not fast for the entire month by likening any month to Ramadan, and do not fast only on Friday so that you do not make it a day of Eid. Rather, if you wish to fast on Friday, then also fast one day before or one day after.