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.")
سَأَلْتُ جَابِرًا ؓ نَهَى النَّبِيُّ ﷺ عَنْ صَوْمِ يَوْمِ الْجُمُعَةِ قَالَ نَعَمْ زَادَ غَيْرُ أَبِي عَاصِمٍ أَنْ يَنْفَرِدَ بِصَوْمٍ