Taqwa (piety) is that you act in obedience to Allah, and hope in His mercy, upon a light from Him; and Taqwa is leaving acts of disobedience to Allah out of fear of Him, upon a light from Him.

 
The Taba'in Talq ibn Habib [Related by Ibn Abi Shaybah in Kitaabul-Eihia (No.99) and it was declared Sahih by Shakyh Albani. (From Fruits of Taqwa)]