Omer, may Allah be pleased with him didn’t invent or innovate. It was the Prophet salla Allahu alaihi wa sallam the first to pray Taraweeh for 4 nights and the companions would pray behind them. The Prophet stopped praying it because he was afraid that Allah would make I mandatory upon the Muslims. That is why, when he died, what he was afraid of was no longer there. That is why Omer reintroduced this beautiful Sunnah.