Quran 2:280 — The Heifer (Al-Baqarah)

If the debtor is unable to pay, wait for a better time. If you give up the loan as a charity, it would be better for you, if you only knew.

[2:279] If you do not, then expect a war from GOD and His messenger. But if you repent, you may keep your capitals, without inflicting injustice, or incurring injustice.

[2:281] Beware of the day when you are returned to GOD, and every soul is paid for everything it had done, without the least injustice.