Sayyiduna Abdullah bin Abbas (may Allah be pleased with them both) said concerning the verse of the Holy Qur'an, "And test the orphans until they reach (the age of) marriage; then if you perceive in them sound judgement, hand over to them their property" [Surah al-Nisa: 6]: In this verse Allah Almighty is saying: Test the orphan children at the time of puberty; if you find some good in them and find them sound in managing their own property, then return their property to them, and also take witnesses over it.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الحجر / 11323
Muqatil bin Hayyan (may Allah have mercy on him) said concerning the saying of Allah Almighty, "And test the orphans" [Surah al-Nisa: 6]: In this the guardians and executors are being commanded: Test them when they reach the age of marriage; "then if you perceive in them sound judgement" [Surah al-Nisa: 6], that is, if they acquire an inclination towards religion and learn to safeguard their property, then "hand over to them their property" [Surah al-Nisa: 6].
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الحجر / 11325