Musannaf Ibn Abi Shaybah

Hazrat Ubaidullah bin Sulaiman Al-Abdi narrates that Hazrat Abu Hakimah Al-Abdi said: We used to write the Qur'an in manuscripts in Kufa. Then Hazrat Ali (may Allah be pleased with him) passed by us while we were writing. He stopped and said: Sharpen the tip of your pen. He says: I sharpened its tip and then I wrote, so he said: Make it clear in the way that Allah has made it clear.