La Genèse 31:7 Halakha : Mishneh Torah, Hiring

.....Just as the employer is cautioned to not steal wages from the poor and not to withhold them, so too are the poor cautioned to not "steal" from the work of his employer by being idle a little here and a little there until he has spent the whole day in deception. Rather, he is obligated to be punctilious with himself regarding time. After all (the sages) were punctilious in the matter of the fourth blessing of the grace after meals, that the employee should not recite it (so as not to take him away from his work), so too the employee is obligated to work with all his strength. Behold, Jacob the righteous said "with all my strength I worked with your father" (Genesis 31:6) he therefore received reward for it, even in this world, as it is stated "and the man profited very much" (Genesis 30:43)