What is the upper age limit of childhood in Islam?

The stage of childhood begins when the fetus separates alive from its mother and ends with puberty, based on the Almighty's saying: "And when your children reach puberty, let them ask permission as those before them asked permission. Thus does Allah make clear to you His verses; and Allah is Knowing and Wise." It is divided into three sections: before the age of discernment (before seven years), from the age of discernment until the tenth year, and from the tenth year until puberty. The child's eligibility differs in each stage; he is commanded to pray in the second stage and disciplined for not praying in the third, and his prayer is not valid before discernment.