Yahya related to me from Malik from Yazid ibn Ziyad that Muhammadibn Kab al-Quradhi said, ''Muawiya ibn Abi Sufyan said from themimbar, 'O people! Nothing keeps away what Allah gives and nothinggives what Allah keeps away. The earnestness of the earnest one doesnot profit him. When Allah desires good for him, he gives himunderstanding in the deen.' Then Muawiya said, 'I heard these wordsfrom the Messenger of Allah, may Allah bless him and grant him peace,on these blocks of wood.' "
USC-MSA web (English) reference: Book 46, Hadith 8
Arabic reference: Book 46, Hadith 1633