What is the ruling on likening children to angels because of their innocence, purity, and serenity?

Angels are honored servants of God. He created them from light. They do not disobey God and they do whatever they are commanded. It appears there is no harm in likening an innocent child to them in terms of purity and freedom from sins, misdeeds, and disobedience. It is stated in Al-Nafrawi Al-Maliki's commentary on the Risala that the wisdom behind the legislation of I'tikaf (spiritual retreat) is to emulate the noble angels in their devotion to worship and their restraint from worldly desires.