Hadith 31-348

وَبِهذَا الإسناد قالَ: قالَ رَسُولَ اللَّهِ‏ صَلَّى اللهُ عَلَيْهِ وَآلِهِ: لا تفرد وَالجُمْعَةِ بصوم.

According to the same documentation, God’s Prophet (S) said, “Do not establish Friday as the only day of the week to fast.”