Mu’awiyah b. Qurrah reports that Abû Al-Dardâ` used to say,
نسال الله إيمانا دائماً و يقينا صادقا و علما نافعا
“We ask Allaah for a lasting faith (Imaan), true certainty and beneficial knowledge.”
Mu’awiyah b. Qurrah then said, “So this indicates that there is a type of faith that does not last, and a type of certainty that is not true, and a type of knowledge that is not beneficial.”
Source: Ibn Battah, Al-Ibanah Al-Kubra Vol. 2 p498.