the orphan's wealth except in the best manner," meaning: that one should preserve his wealth until he reaches his maturity, at which point he should hand over his wealth to him if he perceives in him maturity (rushd).
Qatada said: "When this verse was revealed, it was difficult for them, so they would not mix with them in eating or anything of the sort. Then Allah revealed after that: 'And if you mix with them, they are your brothers in faith.'"
"And fulfill the covenant," meaning: what they have covenanted regarding what conforms to the truth. "Indeed, the covenant will be questioned," meaning: those who gave it will be asked about it.