If I picked up a phone and gave it to my step-father and I know he will use it for BOTH permissible and impermissible things, is there a sin on me? Even if I just picked it up and gave it to him? Would I get sin if he listens to music or does gambling?Jaz?k All?hu Khayran Sheikh!

All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.

As long as you know that this man will use the mobile phone for impermissible purposes, don't give it to him as it would constitute helping him commit abominable acts. The fact that he would use it for permissible purposes as well does not justify it. It is established by scholars that when things might be used for both lawful and unlawful purposes, then they are considered unlawful.

Al-Zarkashi  said in his book Al-Manthoor Fi Al-Qawa‘id Al-Fiqhiyyah: “When things might be used for lawful or unlawful purposes, they are considered unlawful.”

There is no doubt that gambling and listening to music are prohibited. If someone plays gambling games or listens to music, it is incumbent on him to repent to Allah, The Exalted, from these sinful acts by regretting them and resolving never to commit them again in the future. Whoever repents to Allah, The Exalted, He accepts his repentance.

Allah knows best.