Notice this physical impossibility:

But when you give to the needy, do not let your left hand know what your right hand is doing, so that your giving may be in secret.

Hands can’t “know” things and his hearers knew that (why would Jesus make any reference to the mind here?) Jesus explained Himself immediately. But while He could have just said “When you give to the needy, do it anonymously,” He chose the hyperbole.