This depends in part, however, upon the meaning which we attach to the term labor. As the term is commonly understood, it implies some degree, more or less according to the circumstances, of forethought and calculation, strivings of the will, and physical effort. But this is not all. It implies, also, not only effort, but pain. There is something unpleasant in it. In this view of the import of the term, God does not labor; angels do not labor; nor do glorified saints. There is obviously no such thing as labor of this sort in heaven. There is life; there is activity; everything is done which ought to be done; but all labor which involves pain ceases.
And, to a considerable extent, these views are true of the holy man in the present life. He does not cease to be active, and to do what the providence of God calls him to do; on the contrary, cooperating with God in the great work of redemption, he finds and knows no idle moments; but still, the work which he does, ceases so far to possess the ordinary attributes of labor, that he may be said, in a certain sense, to cease from labor.
It will be kept in mind by the reader, that this is not said of the sinful man, nor of the partially sanctified man, but of the man whose soul, freed from the separations of self, has passed into a state of entire union with God. Undoubtedly the rest, which is experienced even by such an one, is not so perfect, in consequence of the imperfections and hindrances of the body, as it will be hereafter; but still, it is so real and great, and besides, so naturally results from the principles involved in holy living, that it deserves to be noticed.
— edited from A Treatise on Divine Union (1851) Part 8, Chapter 7 by Thomas Cogswell Upham. His blog is managed by Craig L Adams and can be found here: http://thomascupham.blogspot.com