From the first portion of your dough to G-d, you must give as a raised-offering. As the raised offering of the threshing floor you must donate.
Bemidbar 15:21
The commandment of giving challah (a loaf) is very straightforward. A part of the dough is set aside to be holy, to be given to the priests, while the rest remains non-sacred and may be eaten without any particular restrictions.
The Torah's ways "are ways of pleasantness, and all its paths are peace."It would seem that the way to peace is equality, while this commandment, like so many others, emphasizes the differences between us. Creating elitist classes encourages jealousy. The priest is different than a Levite, who is himself distinguished from the average Jew. We are fermenting division within every bowl of dough!
The lesson here, however, is that true unity can only be achieved when clear distinctions are made between those who fulfill the various offices of society. Harmony is possible only when every cog of the machine, every unit of the army, knows its proper place and performs its unique function. If there are no separations and distinctions, the result can only be anarchy.
The Hebrew word for "dough" in this verse can also mean "crib" or "bed." In that context, the verse means that our first thoughts, words, and acts when we wake up in the morning should be "raised as a challah offering," i.e., directed and devoted to G-d.
--Kehot's Chumash Bemidbar Synagogue Edition