Praise be to Allah.
If the one who is entering the forum wants to remind his brothers to say tasbeeh and tahleel and takbeer, so he says tasbeeh or takbeer and the other members respond to him, and remember Allaah, then there is nothing wrong with that. It comes under the heading of mentioning Allaah in a gathering, concerning which there is an important, well known hadeeth:
It was narrated that Abu Hurayrah (may Allaah be pleased with him) said: The Prophet (peace and blessings of Allaah be upon him) said: “Allaah, may He be glorified and exalted, says: ‘I am as My slave thinks I am, and I am with him when he remembers Me. If he remembers me to himself, I remember him to Myself; if he remembers Me in a gathering, I remember him in a gathering better than it; if he draws near to Me a handspan, I draw near to him an arm’s length; if he draws near to me an arm’s length, I draw near to him a fathom’s length; if he comes to Me walking, I go to him at speed.”
Narrated by al-Bukhaari (7405) and Muslim (2675).
And he (peace and blessings of Allaah be upon him) said: “No people sit together in a gathering where they do not remember Allaah or send blessings upon their Prophet, but it will be a source of regret and sorrow; if He wills He will punish them and if He wills He will forgive them.” Narrated by al-Tirmidhi (3380) and Abu Dawood (5059); classed as saheeh by al-Albaani in Saheeh al-Tirmidhi.
The reservations in this case have to do with adopting a specific number of times or order of reciting, such as if he starts with tasbeeh and someone else thinks that he has to follow it with takbeer and tahmeed. Believing that it is to be done in a certain order, or that there is a specific number of times for reciting dhikr for which there is no evidence in sharee’ah, or believing that it is Sunnah to recite dhikr in this manner – all of these are bid’ahs or innovations.
The scholars pointed out that singling out a time or place or specific manner for acts of worship that was not narrated (in sharee’ah) is bid’ah or innovation. In that case it is called bid’ah idaafiyyah (additional bid’ah) because it is prescribed in principle, but is rejected because of how it is done.
Al-Shaatibi (may Allaah have mercy on him) said: Bid’ah (innovation) refers to something that is newly invented in matters of religion that appears similar to that which prescribed, by which people intend to go to extremes in worshipping Allaah.
This includes adhering to certain ways and manners of worship, such as reciting dhikr in unison, or taking the birthday of the Prophet (peace and blessings of Allaah be upon him) as an Eid, and so on.
It also includes doing certain acts of worship at certain times for which there is no basis in sharee’ah, such as always fasting on the fifteenth of Sha’baan (yawm al-nusf min Sha’baan) and spending that night in prayer.
End quote from al-I’tisaam (1/37-39).
See also the answer to question no. 11938.
And Allaah knows best.