During Umar's reign as Caliph, hadith were being narrated by the people. Many sources state that it was Umar himself who was the first person to ban hadith. Certainly during his rule Umar strictly followed the policy of banning the hadith and he prohibited reporting and transmission of hadith altogether.

What did Prophet Muhammad say about Umar?

And while a man was driving a cow with a load on it, it turned towards him and spoke to him saying, 'I have not been created for this purpose, but for ploughing." The people said, "Glorified be Allah." The Prophet said, "But I believe in it and so does Abu Bakr end 'Umar."

How many hadith did Bukhari collected?

Al-Bukhari traveled widely throughout the Abbasid empire from the age of 16, collecting those traditions he thought trustworthy. It is said that al-Bukhari collected over 300,000 hadith and included only 2,602 traditions in his Sahih.