Take it seriously — the Prophet ﷺ compared the righteous companion to the carrier of musk, from whom you gain either a gift, a purchase or a good scent, and the evil companion to the blacksmith's bellows, which either burn your clothes or leave you with a foul smell (Ṣaḥīḥ al-Bukhārī 5534; Ṣaḥīḥ Muslim 2628); and he ﷺ said a man is upon the religion of his close friend, so let each of you look at whom he befriends (Sunan Abī Dāwūd 4833, ḥasan). But an outright ban with nothing offered in its place usually just drives the friendship underground and teaches the child to hide things from you. The prophetic approach is replacement: give them better company — a halaqah, a masjid youth programme, righteous cousins, a sports circle with good company — open your home so their friends are under your eyes, and keep the relationship warm enough that they still tell you the truth. Explain your reasons rather than issuing decrees, and make duʿāʾ for the child and for their friend, since guidance is from Allah alone.
Q&A · Youth & Parenting
What should parents do about a child's bad friends?
Evidence — the daleel
On deen2u
Informational, not a personal fatwa. Consult a qualified scholar for rulings on your situation.