Is greeting Jummah mubarak to a fellow muslim, family or friend Biddah?
There is no doubt that Friday is the most blessed day of the week for Muslims but greeting other Muslims by saying "Jumuah Mubarak" is not proven from Sunnah or the practice of the Sahabah.
Therefore it is best to avoid it. If someone says it considering it an act of virtue then it will become Bid'ah and forbidden.
If one casually said it without considering it an act of virtue then it may be tolerated.
And Allah knows best.
Mufti Ikram ul Haq
Fatwa Center of America