It came to a shock on me that saying have a blessed jummah (Friday) is an innovation in Islam because it has never been said by the sahabis nor by our beloved prophet (saw).
1 Answer
Saying "Eid Muarak" or any good greetings for Eid is not a bidaah since the sahabah used to do it:
Jubayr ibn Nufayr said: “At the time of the Prophet, peace and blessings be upon him, when people met one another on the day of `Eid, they would say: Taqabbal Allahu minnaa wa minka (May allah accept yours and our good deeds).”
[Reported by Al-Albani with an authentic chain of transmission]
As for Jummah. There is no harm in doing so. Unless you consider this as a sunnah (keep doing it every Friday) or you think saying "Jummah mubarakh" will increase your good deeds. Then this is considered a bidahh.