I know it's okay for small children to have "characters" as toys, such as stuffed animals, but I'd just like to interject about it if you don't mind.
I do think it's unhealthy for small children to get too involved with these things. Like getting too many toys that represent characters and getting too drawn into that fictional world that they represent. I can only speak from personal experience but when I was four (and the years after that) I was really into that. I loved Disney movies and had lots of toy animals/dinosaurs and Jurassic Park figurines of all the Juarssic Park cast. I became absorbed into that world at the expense of the real world around me because I felt it was better and more exciting inside my imagination than out there... I really believe that messed me up and drew me into escapism. I still find myself sometimes trying to escape into my own little world, I really have to force myself not to. And I saw it in the children around me, growing up with escapism being the highlight of their life, replacing their cartoons, stuffed toys and action figures with football and pop cultures, or soap operas, or alcohol (or worse).
Even for children brought up into a muslim background this is something to be wary of - I have seen it myself, children moving away from their faith because 1) it's not enforced enough at home or it's enforced but not really understood well and 2) they've had no restrictions on their escapism (toys, video games, etc). I also think there is a correlation with that and discipline.
So, I dunno, just an idea to maybe get him something that's not so much colours and tassels and things and maybe something more wholesome. I know some might think "he's only four" but I really believe it starts young this escapism mindset. It did with me anyway, much younger than four.