Ijtihad Of Umar RA In Taraveeh
According to Ghamidi sahib Traveeh are tahajjud prayer. The prophet once offer them in the mosque in a Ramadan but did not come out for the fourth day as the companions seemed very eager to say this prayer behind him. As you mentioned the Hadith. In the time of Umar when he saw people in Ramdan saying their nafal prayers individually which causes noise in the mosque, he disliked it and made an executive order to say nafal prayer in mosque under one imam. Here started the rite of congregational prayer of this Thajjud prayer in Ramadan which later took the name of Traveeh. Which means taking rest, this rest was taken after every two or four rakaat.