Sunan Ibn Majah Book 34, Hadith 26
the Messenger of Allah (saas) said: "May Allah have mercy on us and on our brother of 'Ad." (i.e., Prophet Hud alay-salaam).
"The Messenger of Allah (saas) said: 'There is no supplication that a person can say that is better than: Allahumma inni as'aluka al-mu'afah fid-dunya wal-akhirah (O Allah, I ask You for Al-Mu'afah in this world and in the Hereafter).'"
the Messenger of Allah (saas) said: "It is necessary that you do not become hasty." It was said: "What does being hasty mean, O Messenger of Allah?" He said: "When one says: 'I supplicated to Allah but Allah did not answer me.'"