Al-An'am - 6:152

وَلاَ تَقْرَبُواْ مَالَ الْيَتِيمِ إِلاَّ بِالَّتِي هِيَ أَحْسَنُ حَتَّى يَبْلُغَ أَشُدَّهُ وَأَوْفُواْ الْكَيْلَ وَالْمِيزَانَ بِالْقِسْطِ لاَ نُكَلِّفُ نَفْسًا إِلاَّ وُسْعَهَا وَإِذَا قُلْتُمْ فَاعْدِلُواْ وَلَوْ كَانَ ذَا قُرْبَى وَبِعَهْدِ اللّهِ أَوْفُواْ ذَلِكُمْ وَصَّاكُم بِهِ لَعَلَّكُمْ تَذَكَّرُونَ
[6:152]
And do not approach the property of the orphan except in the best manner until he attains his maturity, and give full measure and weight with justice-- We do not impose on any soul a duty except to the extent of its ability; and when you speak, then be just though it be (against) a relative, and fulfill Allah's covenant; this He has enjoined you with that you may be mindful;
And come not nigh to the orphan's property, except to improve it, until he attain the age of full strength; give measure and weight with (full) justice;- no burden do We place on any soul, but that which it can bear;- whenever ye speak, speak justly, even if a near relative is concerned; and fulfil the covenant of Allah: thus doth He command you, that ye may remember.
And approach not the wealth of the orphan save with that which is better, till he reach maturity. Give full measure and full weight, in justice. We task not any soul beyond its scope. And if ye give your word, do justice thereunto, even though it be (against) a kinsman; and fulfil the covenant of Allah. This He commandeth you that haply ye may remember.