Some of the people squander time and waste their time with actions even in that which is impermissible. For this reason you find some of those people who are heedless, they make the expression using the words ‘killing time’ as if (time) is an enemy!! The time is a type of wealth and what goes away from it does not return. The one who has intellect, he is the one who values his time and he is cautious from killing and squandering it.
– Shaykh Abdur-Razzaaq al-Badr