the 12 imam's

Imam Bukhari one time went to learn about Hadith from the scholars with other fellow students. For 12 full days they went and were taught.

His fellow students all brought pens and paper, and were eagerly writing everything down. But Imam Bukhari, he had no pen and no paper, he just sat there.

This went on for 12 days, after which his fellow students told him to leave because he was wasting his time just sitting there and not writing anything down.

They told him they had written down 15.000 ahadeeth in those 12 days, and Imam Bukhari had not written down a single Hadith so far.

Imam Bukhari told them that he is not a man who wastes his time. He then ordered them to take out their notebooks and proceeded to narrate to them all 15.000 ahadeeth from memory!