is saying allah hafiz or jummah mubarak a bid'ah

All perfect praise be to Allaah, the Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His Slave and Messenger.

In principle, we do not see anything wrong with saying the phrase "Allaah Hafiz" as this is informing of something that is true. Ash-Shawkaani said in Fat-h Al-Qadeer: “Al-Haafith (The Guardian) is in reality Allaah The Almighty, as in His saying (which means): {But Allaah is the best Guardian, and He is the Most Merciful of the merciful.} [Quran 12:64] The meaning of the verse is: “Allaah is the best Guardian amongst you.” Ka’ab Al-Ahbaar said: “When Prophet Ya’aqoob (Jacob) said {Allaah is the best Guardian}, Allaah said: “I swear by My Glory and My Majesty, I will bring you back both of your sons after you relied on Me (put your trust on Me).”

So, we ask Allaah to protect us and you from all evil, but it is not permissible to replace the greeting of Islam (Assalaamu 'Alaykum) by the phrase "Allaah Hafiz"; for more benefit, please refer to Fatwa 83956.

As regards saying ‘Jumu’ah Mubaarakah’ [i.e. have a blessed Friday], then if a Muslim abides by saying this to his Muslim brother after the Jumu’ah prayer or every Friday, we do not know this to be from the Sunnah of the the Prophet nor is it known from his companions, nor did any scholar say that this is permissible. Therefore, this is considered a newly introduced innovation (Bid’ah), especially if one says so as an act of worship or while believing that this is a Sunnah. It is confirmed that the Prophet said: ''Whoever does an act that is not in accordance with ours (i.e. Islam) it is rejected.” [Al-Bukhari and Muslim] Also, another Hadeeth reads: “Whoever introduces into this matter of ours (i.e. Islam) that which is not part of it, his act is rejected.” [Al-Bukhari and Muslim]

Shaykh Salih Al-Fawzaan, may Allaah protect him, was asked – as published on his official website – about the ruling on a Muslim saying to his Muslim brother ‘Jumu’ah Mubaarakah’ every Friday either by mobile messages or in forums. He replied saying: “This has no basis and it is an innovation, and it is not permissible to congratulate each other on (the occasion of) the day of Friday; no evidence has been reported (in this regard in religious texts) and the Salaf (righteous predecessors) did not do so, so it is an innovated act.”

Allaah Knows best.