פּירוש אויף בראשית 3:19

בזעת אפיך IN THE SWEAT OF THY FACE — after you have taken all this great trouble.

בזעת אפיך תאכל לחם, if you prefer to eat bread to eating grass, herbs, you will have to toil in the sweat of your brow in order to produce cereal grain which can be turned into bread. Even though the whole body will perspire, not just the brow, the Torah mentions the face especially, seeing that this is where his perspiration will be most visible. Furthermore, a face does not begin to perspire until one has exerted oneself considerably. Man will have to be fatigued by a variety of strenuous activities before finally being able to consume bread. He has to plough, to sow , to remove weeds, to cut the grain, to thresh the kernels in their husks, to winnow, to grind the kernels into flour, to knead the dough and to bake it.

אל עפר תשוב, you will revert to dust, just as I had told you “on the day you eat from it you will surely become mortal.” (not that he would actually die on that same day).