moslike:

My thoughts based on my reading of the Quran.

4/19 tells us not to forge relationships through force or coercion. 4/5 commands us not to hand over trusts to those who lack the capacity to make informed decisions. 30/21 says God “placed between you love and mercy,” which tells us that the relationship should be based on mutual feelings. Children lack emotional intelligence and stability and are not comparable to adults.

2/221 commands not to make unions with the mush’rikīn “even if s/he impresses/pleases you [aʿjabakum]”. The implication being that being impressed/pleased by a person in normal circumstances is an acceptable reason to marry said person. But to be impressed/pleased by someone implies you have the ability to observe and understand the traits on display. A person not of a mature mind lacks the ability to assess what is necessary in a spouse, therefore can not form an opinion on impressive vs unimpressive life-partner traits. Children may be impressed by chocolate and unimpressed by vegetables, but that’s only because children lack the understanding and knowledge of good eating habits. What then of assessing a potential spouse?  2/232 commands us not to hinder unions when “they mutually agree between them [tarāḍaw baynahum] with kindness/fairness [bil-maʿrūfi].” Again, to mutually agree upon something implies both parties understand what is being agreed upon. This tells us both parties must be of mature and sound mind to enter into a marriage contract.

The separation/annulment of an agreement in 2/237 speaks about what “you ordained [faraḍtum] for them as an obligation.” As per 2/232, this would had to have been mutually agreed beforehand, therefore both parties must have the ability to understand such specifics. Furthermore, there are several passages in the Quran that deal with annulment/separation and how each party has an obligation towards the other. For example, in 2/228 it mentions in the event of separation process there may be a situation where, “they wish a reconciliation” [in arādū iṣ’lāḥan]. Such a reconciliation would be a sham if the one married was a child to begin with who lacked the capacity to understand the original contract. The Quran expects ones who enter marriage contracts to have the ability to go through a divorce process with full understanding and agency.

In the story of Yusuf, we see that in 12/19 he is found in a well as a boy [ghulāmun]. In 12/22-3 we see that only after he reached maturity [ashudda] did the woman attempt to seduce him. 18/82 also suggests reaching maturity is about physical maturity. By these verses we can attempt a simple deduction:

1) 6/152 tells us not to hand over trusts to people who have not reached maturity [ashudda].
2) 4/5-6 commands us not to hand over trusts to those who have yet reached the ability to make contracts/unions [l-nikāḥ].
3) Therefore, the minimum age in which one can do the nikāḥ is when they reach ashudda, physical maturity.

The Prophet himself would have been bound by these constraints for he says, “I follow nothing except what is revealed to me.” (6/50)