It is not permissible for you
to refer the one who lent you ten thousand Riyals to the person who owes you money and is delaying repayment and to add two thousand Riyals to make up for the first's procrastination because this extra amount is Riba (usury/interest) which is Haram (prohibited) according to the Islamic Shari`ah (Islamic law). (Part No. 13; Page No. 308)
May Allah grant us success. May peace and blessings of Allah be upon our Prophet Muhammad, his family and Companions!