Really and did you refuse it again a second time? Also if he try's to steal it tell his mom or so on if he try's to. Reason i've had my sister steal my whole collection yet she now has it, But i didn't stop me from stating anew one so hehe. yeah...
Always tell a parent or there grown up if there planning to steal that or tell your friend to shop for it online on the card shop or something to find one exactly like it and instead of stealing it the site or whatever can deliver it to your friend in ideal..
So that away he won't steal from you @StarCosmicoGalactus so you know and you two can still be friends and have the same cards without stealing from each other you know.?,
So yeah stealing can be wrong but eh? unless it's for something similar and treasure always have a ideals in mind so you two can sort it out in a talk over and don't fight over it nor steal it okay?