Narrated Sa'd bin Abi Waqqas:
The Prophet said, "The most sinful person among the Muslims is the one who asked about something which had not been prohibited, but was prohibited because of his asking."
Vol: 009 Book: 092 Hadith: 392
A Selected Dua
There is none worthy of worship but Allah.
Info: Abu Dawud 3/190. See also Al-Albani, Sahihul-Jami' As-Saghir 5/432.