https://sunnah.com/bukhari:2010
So this is the hadith it basically quotes Umar Bin Al-Khattab saying that the taraweeh prayer was a good innovation
This is the scan⬆️
What did Umar Ibn Al-Khattab RA mean by Bid’ah?
As for innovations البدع, it is the plural of innovation بدعة: it is everything which does not have any prior example.
Linguistically, the word encompasses what is both praiseworthy and blameworth In the usage of the people of the legislation
(i.e. Scholars) it is specifically for what is blameworthy and if it is used in connection to what is praiseworthy,
then it is upon its linguistic meaning. …»
So in conclusion when Umar رضي الله عنه used the term ‘bid’ah’ he was referring to the linguistic bid’ah.
And the linguistic bid’ah is used to praise something. Umar رضي الله عنه praised that the taraweeh was prayed in congregation.
This is NOT referring to the shar’i bid’ah (the actual innovation)
Here is Ibn Kathir saying that there is a linguistic bidah and a shari'i bidah. And he uses the hadith of
Umar AS to prove the linguistic bidah.
Shaykh al-Albani stated:
The words of ‘Umar, “What a good innovation this is”, do not refer to innovation in the technical shar‘i sense,
which means introducing something into the religion with no precedent. Rather he was referring to innovation in a
linguistic sense. and sheikh Albani continues to say this is because it was in accordance with what the Prophet (SAWS)
did, it is Sunnah and is not an bidah, and he only described it is good because of that.