I'm a beginner learner and don't know which one is right. I mean, whether I should use "for" in the sentence or not. (also, one of myfriends told me that each of the sentences had a different meaning. But I don't know, that's what they told me.) Please, explain to me. I was told I could find help here. Thank you all!7
To make sure that [fact] is to confirm, to one's own satisfaction, that [fact] is true.
Both sentences are rather strange; and they do differ in meaning.
The second sentence, without “for you”, seems to mean that, by telling the listener something, the speaker confirms for himself that the speaker is good. I think that's strange.
The first version, with “for you”, suggests that the listener can use the information to confirm the speaker's goodness. But “I tell you this for you to do something” does not feel right to me. I would replace “for you to” with “to help you” or “so that you can”.