Why should one not tell of one's bad dreams to avoid their realization, especially if one's visions in dreams often come true?

Visions are of three types: self-talk, fright from Satan, and good tidings from Allah. Whoever sees a vision that he dislikes should seek refuge with Allah from its evil and from the evil of Satan, and should spit three times, and should not narrate it to anyone. Indeed, it will not harm him. Whoever does this, the bad vision will not harm him, no matter what it is.