Authentic Supplication Number 172.

The Prophet  said "There will be no contagiousness, nor drawing bad omens [pessimism], and the truest of these is the drawing of good omens [optimism]. They said: What is the drawing of good omens? He said: A good word that a person hears.

Reporters.
Al-Albani said it was reported both Al-Bukhari, and Muslim by way of `A'ishata, and he included this hadeeth in The Authentic of Good Sayings as #190.