Al-An'am 6:152

Wala taqraboo mala alyateemiilla billatee hiya ahsanu hattayablugha ashuddahu waawfoo alkayla walmeezana bilqistila nukallifu nafsan illa wusAAaha wa-ithaqultum faAAdiloo walaw kana tha qurbawabiAAahdi Allahi awfoo thalikum wassakumbihi laAAallakum tathakkaroon

And do not approach the orphan's property except in a way that is best [i.e., intending improvement] until he reaches maturity. And give full measure and weight in justice. We do not charge any soul except [with that within] its capacity. And when you speak [i.e., testify], be just, even if [it concerns] a near relative. And the covenant of Allāh fulfill. This has He instructed you that you may remember.

Do not approach the property of the orphan, except with the best possible conduct, until he reaches maturity. Give full measure and full weight in all fairness- We do not obligate anyone beyond his capacity - and be just when you speak, even though the one (against whom you are speaking) is a relative; and fulfill the covenant of Allah. This is what He has enjoined upon you, so that you may observe the advice.