If the adhān is called by a child who has the ability to discern, it is considered valid. The discerning child is one that is between the age of seven and puberty. He is termed discerning because he has the ability to understand speech addressed to him, and to answer accordingly. Some scholars also say: The discerning child should not be identified by age but by the presence of this characteristic.
As for those who identify discernment by age, they support their view with the saying of the Prophet (صلى الله عليه وسلم): “Command your children with prayer by completion of the age of seven, and beat them in relation to it by the age of ten.”1 Here, the first age at which prayer is commanded has been specified as seven. This proves that before this age, it is invalid to command them to do so. The reasoning for this may be that they lack the faculties to understand the command itself, or that they lack the physical ability to fulfil it. If we adopt the first reason, then completion of the age of seven becomes the limit of discernment. If we adopt the second reason, then age in of itself is not the sole criteria of discernment.
As for those who restrict the measurement to the presence of the discernment itself, rather than age, they reason that discernment is related to the ability to reason. Thus, if this ability is present in a child then it is attributable to him. The discerning child is any child that is able to understand speech that is addressed to him and answer coherently.
However, completion of the age of seven is usually the limit at which most children would have gained this discerning ability. We mean by this that he fully comprehends the meaning of speech. For example, if you were to ask him to bring you something—like water—he would go and bring it.
[Q]: Is the adhān called by the discerning child valid or invalid?
[A]: According to the composer [al-Ḥajūrī], the adhān of such a child is valid. For example, if a town has no other person to call the adhān except for this discerning child, and he calls the adhān, then this is sufficient. The reasoning for this is that the adhān is a form of remembrance. Engaging in remembrance does not have the prerequisite of the person having reached the age of puberty. Any child [before the age of puberty] will only have his righteous actions written for him, and his misdeeds are not recorded. Thus, if he engages in the remembrance of Allāh, Allāh will have recorded his engagement in an act of righteousness for which he will be rewarded. That is, his remembrance is valid such that if he was to call the adhān, we should suffice with it.
Other scholars say: The adhān of the discerning child is invalid because his speech is considered untrustworthy, nor is he one whose opinion is considered dependable. For example, he may not know when the sun has begun its descent from its zenith [the time for Ẓuhr], or be able to identify the time when the shadow of an object is equal to its height [the time for ʿAṣr].
Some scholars have elaborated on this issue saying: If he calls the adhān in the presence of another then there is nothing wrong with this. If there is no one with him, then we should not depend on him for the adhān, except if he is accompanied by a grown-up [one has reached the age of puberty], of sound intellect, who is knowledgeable of the timings of the prayers who is able to direct him when to perform the call. This is the correct opinion in this issue.
 Authentic: narrated by Abū Dāwūd: 495 and graded authentic by Shaykh al-Albānī in lIrwāʾ al-Ghalīl’: 247.
Source: Al-Sharḥ al-Mumtiʿ 2:71-72
Translated by: Riyāḍ al-Kanadī