Surat An-Nisā' - سورة النساء

وَآتُوا الْيَتَامَىٰ أَمْوَالَهُمْ ۖ وَلَا تَتَبَدَّلُوا الْخَبِيثَ بِالطَّيِّبِ ۖ وَلَا تَأْكُلُوا أَمْوَالَهُمْ إِلَىٰ أَمْوَالِكُمْ ۚ إِنَّهُ كَانَ حُوبًا كَبِيرًا

Muhsin Khan: And give unto orphans their property and do not exchange (your) bad things for (their) good ones; and devour not their substance (by adding it) to your substance. Surely, this is a great sin.