What should I do as the parent of a 12-year-old child, after his friend's mother saw him drowning in the sea in Egypt in a dream, and to what extent should such visions be taken into account, despite the neighbor's previous righteous and fulfilled visions?

The vision of a believer is predominantly truthful and constitutes one of forty-six parts of prophethood. As time approaches [the Day of Judgment], the vision of a believer will scarcely prove false. The congruence of a vision with reality is well-known, but there is no definitive way to be certain of its fulfillment.

You should frequently supplicate and seek refuge with Allah from the evil of this vision. If you dream a dream you dislike, spit to your left and seek refuge with Allah from it, and it will not harm you.

Supplication is beneficial for what has descended and for what has not descended. There is no harm in taking precautions against and avoiding anticipated disliked matters.