 Already at the time of the Mishnah, constituted the second part of a standard "Shema" prayer that the priests recited daily, following and preceding  The first three chapters of tractate Berakhot in the Mishnah, Jerusalem Talmud, and Babylonian Talmud and the first two chapters of tractate Berakhot in the Tosefta interpreted the laws of the "Shema" in and 

Rabbi Joshua ben Korhah taught that the "Shema" prayer puts before so that those who say the prayer should first accept upon themselves the yoke of Heaven's sovereignty and then take upon themselves the yoke of the commandments.And comes before because applies both day and night (since it mentions all the commandments), whereas is applicable only to the day (since it mentions only the precept of the fringes, which is not obligatory at night).Reading "To love the Lord your God and to serve Him with all your heart," a Baraita equated service of the heart with prayer.