One should not unappreciatively question or inspect a gift too closely.

Alternative form of don't look a gift horse in the mouth

(idiomatic) To return to something that previously caused harm.

Enthusiasm of an inexperienced person will cause harm.

A response to someone wishing for something, conveying that merely wishing for something has no effect or is of no use.

Alternative form of if wishes were horses, beggars would ride

(idiomatic) To attempt to prevent a problem that has already occurred.

(medicine, informal) When diagnosing a patient's symptoms, common ailments should be considered as more probable than rare ones.

You can show someone how to do something, but you can't make them do it.

Alternative form of you can lead a horse to water, but you can't make it drink