Halakhah zu Dewarim 23:26

That the worker not eat during work time: That the wage-worker not eat during his work from the thing with which he is involved. Even though it is permitted to eat from it not during work - and that is when he is going from row to row - when he is working with that which is connected to the ground, it is not permitted to eat during work time (see Sefer HaMitzvot LaRambam, Mitzvot Lo Taase 267). And about this is it stated (Deuteronomy 23:26), "but you must not put a sickle to your neighbor’s grain." As they, may their memory be blessed, said (Bava Metzia 87b) [that the word,] "sickle" is to include all that requires the sickle, and at the time of the sickle - meaning to say at harvest time, do not harvest for yourself. And it is already known that this verse is coming [to refer] to a wage-worker. And the explanation of "When you come" is meaning to say, when you come to your wage-work to be involved with the owner of the field; as Onkelos translates it, "When you are employed" (Onkelos Deuteronomy 23:26).