Allah Almighty says: "Until they reach (the age of) marriage." [Surah al-Nisa: 6]
Imam Mujahid (may Allah have mercy on him) said: "(It means) puberty (wet dreams)."
Sayyiduna Ali (may Allah be pleased with him) said that the Messenger of Allah (peace and blessings be upon him) said: "The pen has been lifted from three people: from the sleeper until he wakes from his sleep, from the child until he has a wet dream, and from the insane person until he regains his senses."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الحجر / 11308