To borrow money to someone involved in haram?

Source: Muqbil Shaykh al-Wadi'i (rahimahullah) in Tuhfatul Mujib page 63

Question:

Do you lend money to someone they know doing haram?

Answer:

Allah Subhanahu Wa Taal says (in meaning)

"And cooperate in righteousness and godly affairs and cooperate when it comes to sinful and evil."

(Surah Al Maida 2)

So you should not give him a loan and not help him in the evil he's doing.