Darkness of the Heart

'Abdullah ibn Mas'ud (radyAllahu`anhu) said, “Four things are from the darkness of the heart – a full stomach without caring [whether it is halal or haram]; keeping the company of oppressors; forgetting past sins; and being under the delusion that one’s lifetime will surely be long. There are another four things that are from the illumination of the heart – an empty stomach because of caution; accompanying the righteous; remembering past sins; and not expecting to live for long.”