What is the ruling on the prayer of one who was late for the Friday prayer and did not attend except at the beginning of the sermon or when it was about to end?

If a boy has not reached puberty, the Friday prayer is not obligatory upon him, because one of the conditions for the obligation of Friday prayer is puberty, as evidenced by the saying of the Prophet (peace be upon him): "The pen has been lifted from three: from the child until he reaches puberty." However, he is discerning, and the Friday prayer is valid for him, starting from the sermon. Therefore, he should not be negligent in attending the sermon, because missing the sermon causes him to miss a great deal of good, and he might become accustomed to laziness. Nevertheless, if he misses the sermon but catches the prayer, even one rak'ah of it, his prayer is valid.