From when do we recite the Shema in the morning? From when one can distinguish between techeiles and white. R’ Eliezer says: between techeiles and leek. And one must finish it by sunrise. R’ Yehoshua says: By three hours, for such is the way of princes, to rise by three hours. One who recites from then and onward does not lose; [he is] like a person reading from the Torah.

Until when may one plow in a field of trees on the eve of the seventh [year]? Beis Shammai say: As long as it is good for the fruit. But Beis Hillel say: Until [the festival of] Shavuos. The opinion of these is close to being like the opinion of these.