An-Nisa · 4:2

2. Guardians, give orphans (whose fathers have died and who have not yet reached maturity) their wealth in full when they come of age and have sound judgement. Do not exchange what is permitted for what is prohibited: taking what is good and valuable from the property of the orphans and replacing it with something bad and of little worth from your own property. Also, do not take the property of the orphans and combine it with your own wealth – that is a great crime before Allah.