One who acts without knowledge is like …

Imam al-Hasan al-Basri said:

“One who acts without knowledge is like one who travels off the path; and the one who acts without knowledge corrupts more than he rectifies.

So seek knowledge in a way that does not harm your worship, and seek to worship Allah in a way that does not harm your seeking of knowledge.

For verily, there were people {the Khawarij} who sought to worship Allah but abandoned knowledge until they attacked the Ummah of the Prophet Muhammad ~ peace and blessings of Allah be upon him ~ with their swords.

But if they had sought knowledge, it would not have directed them to do what they did.”

{Related by Hafiz Yusuf Ibn ‘Abd Al-Barr, Jami’ Bayan Al-’Ilm wa Fadlihi}