It is disliked to single out Friday for fasting, unless it coincides with a day that one customarily fasts Sahih Muslim 1144 b
Translation
Abu Huraira (Allah be pleased with him) reported Allah's Apostle (ﷺ) as saying
Do not single out the night (preceding) Friday among the nights for prayer and do not single out Friday among days for fasting but only when anyone among you is accustomed to fast (on dates) which coincide with this day (Friday).