Musar zu Mischlej 28:9

You should know that zeal is the very beginning of all ethics. For no man can be perpetually bent over his book. He must eat, sleep and perform his bodily functions. Therefore, it requires eagerness and care to return to one's book and to study. One should not muse "the day is still long and the year is still long." Concerning this our Sages, of blessed memory, said : "Do not say, 'when I have some free time, I will study' — perhaps you will never be free" (Aboth 2:4). Nor should a man say, : "It is already evening — if I start studying now, I will have to stop in a little while to pray," for it is better to spend one hour in study even if only to learn one saying, than to do any other thing in the world. Concerning this it is said, "He that turneth away his ear from hearing the law, even his prayer is an abomination" (Prov. 28:9). And thus it is written : "The law of thy mouth is better unto me than thousands of gold and silver" (Ps. 119:72). And thus it is also written, "For a day in Thy courts is better than a thousand" (Ps. 84:11), on which the Talmud comments : The Holy One, Blessed be He, said, "I prize one day of your studying Torah more than the thousand sacrifices which your son Solomon will offer upon the altar" (Shabbath 30a).