From Ibn 'Abbaas (radiyallaahu 'anhumaa) who said that Allaah's Messenger (salallaahu 'alaihi wa'sallam) said:
There are two blessings which many people lose: health and free time.
So how can one who has no free time preoccupy himself with this world? How can one whose time is filled experience free time? So consider, may Allaah have Mercy upon you, what one of the scholars said about one of the Imaams: 'I was a neighbour of his at the school in Cairo, my house was above his house. For twelve years, I did not awake on any night, at any hour of the night except that I noticed candle light in his house and he was occupied with knowledge. Even when he was eating, his books would be with him and he was occupied with them. From those things upon which the Muslim personality is built is: