Al-Isra' - 17:34

وَلاَ تَقْرَبُواْ مَالَ الْيَتِيمِ إِلاَّ بِالَّتِي هِيَ أَحْسَنُ حَتَّى يَبْلُغَ أَشُدَّهُ وَأَوْفُواْ بِالْعَهْدِ إِنَّ الْعَهْدَ كَانَ مَسْؤُولاً
[17:34]
And draw not near to the property of the orphan except in a goodly way till he attains his maturity and fulfill the promise; surely (every) promise shall be questioned about.
Come not nigh to the orphan's property except to improve it, until he attains the age of full strength; and fulfil (every) engagement, for (every) engagement will be enquired into (on the Day of Reckoning).
Come not near the wealth of the orphan save with that which is better till he come to strength; and keep the covenant. Lo! of the covenant it will be asked.