Communal du’aa’ after Taraaweeh prayer

My question is about the saheeh Sunnah with regard to Taraaweeh prayer
and what innovations have been introduced into it, and thecommunal
du'aa' after Taraaweeh prayer. May Allaah reward you with allgood on
my behalf and on behalf of the Muslims.
Praise be to Allaah.
With regard to the first part of your question, please see the section
on Taraaweeh prayer and Laylat al-Qadr under the heading of Fasting on
this website.
With regard to communaldu'aa' after Taraaweeh prayer, this action is
an innovation (bid'ah). The Prophet (peace and blessings of Allaah be
upon him) said, "Whoeverdoes an action that is not part of this matter
of ours(Islam), will have it rejected." Narrated by Muslim, 3243.
What was narrated from the Prophet (peace and blessings of Allaah be
upon him) was that after Taraaweeh prayer he would say, "Subhaan
al-Malik al-Quddoos (Glorybe to the Sovereign, the Most Holy)", three
times, raising his voice on the third time.
Ahmad (14929), Abu Dawood (1430) and al-Nasaa'i (1699) narratedthat
Ubayy ibn Ka'b (may Allaah be pleased with him) said: The Messenger of
Allaah (peace and blessings of Allaah be upon him) used to recite in
Witr "Sabbih isma Rabbika al-A'la (Glorify thename of your Lord, the
Most High)…" [i.e., Soorat al-A'laa 87] and Qul yaa ayyuha'l-kaafiroon
(Say (OMuhammad), 'O al-Kaafiroon (disbelievers))…'" [i.e., Soorat
al-Kaafiroon 109] and "Qul Huwa Allaahu ahad (Say (O Muhammad),'He is
Allaah, (the) One)…" [i.e., Soorat al-Ikhlaas 112]. And after he said
thetasleem he would say "Subhaan al-Malik al-Quddoos, Subhaan al-Malik
al-Quddoos, Subhaan al-Malik al-Quddoos (Glory be to the Sovereign,
the Most Holy; Glory be to the Sovereign, the Most Holy; Glory be to
the Sovereign, the Most Holy)", raising his voice. Classed as saheeh
by al-Albaani in Saheeh al-Nasaa'i, 1653.
Then in Witr prayer the imam will recite du'aa al-qunoot and the
worshippers will say Ameen behind him, as Ubayy ibn Ka'b (may Allaah
be pleased with him) used to do when he led the people in praying
Taraaweeh at the time of 'Umar (may Allaah be pleased with him). So
there is no need to introduce this bid'ah. Howtrue are the words of
the one who said, "All goodness is in following those who came before,
and all evil is in the innovation of those who came later."
And Allaah knows best.