İt’s impossible to marry the children. To reach the puberty is not adequate for marriage, it needs to reach the maturity, too. The maturity age may change in different countries and societies, but a nine-years-old child can not be mature nowhere.
The Glorified Allah commands in 6.verse of Nisa in Qur’an:
“And try the orphans until they reach the age of marriage; if then you find maturity – judgement in them, release their property to them; but do not consume it wastefullyn and hastily fearing that they should grow up. Whoever is rich, he should try to be virtuous, if he is poor, let him have for himself what is reasonable. When you release their property to them, take witness in their presence; Allâh is All¬Sufficient in taking account.”
The people sufficient to evaluate the 2. And 3. Verses of Surah Nisa together with this verse can recognize that maturity is a condition for marriage.
According to this verse, in our religion the marriage age is “maturity age”. Maturity age begins with puberty, but may change from person to person. For example person A can reach the maturity in the same time with his puberty, but the person B may reach the puberty several years before reaching his maturity. The person’s family or the authorities has to decide if their child is mature enough, or not. That is one of the reasons that our religion does not accept the matrimony without the permission of family or authorities.