His statement, “an adult,” implies that a boy may lead another boy in prayer, and this is indeed the case. This is the view adopted by the author, may Allah have mercy on him.
The second view is that an adult’s prayer behind a boy is valid.
The evidence for this is the report established in Sahih al-Bukhari that Amr ibn Salamah al-Jurami led his people in prayer when he was six or seven years old. This was because, as an intelligent boy, he would meet the passing riders and memorize the Quran from them. When his father returned from the Messenger of Allah, peace and blessings be upon him, he related to them that the Prophet, peace and blessings be upon him, said: “… When the time for prayer comes, let one of you call the adhan, and let the one who knows the most Quran lead you in prayer.” He said: “They looked around and found that none knew more Quran than I did, because of what I had learned from the passing riders. So they put me forward to lead them, when I was six or seven years old. I had a cloak, and when I prostrated, it would draw up and expose me. A woman from the tribe said, ‘Will you not cover your reciter’s backside from us?!’ So they bought some cloth and made a shirt for me. I never rejoiced over anything as I rejoiced over that shirt.” (1)
As for the hadith, “Do not put your boys forward to lead you in prayer,” (2) it has absolutely no basis and is not authentically reported from the Prophet, peace and blessings be upon him.
As for the reasoning, we have already learned the principle that there can be no analogy in the presence of an explicit text, because analogy is an opinion that may be right or wrong, and it is not permissible to speak about religion on the basis of opinion. When we possess an authentic hadith, personal opinion is nothing before it.