"In the second book I will include all the commandments that apply constantly and that we were commanded to observe in order to love G-d and remember Him always, such as the reading of the shema, prayer, phylacteries, and the priests' blessing; circumcision is included since it is a sign in our flesh to remind us always, at times when there are no phylacteries or fringes or the like. And I have called this book the Book of Love."

6. Reciting the Shema - Kerias Shema

Twice each day one must recite the shema, which consists of three sections of the Torah: "Hear, O Israel...",¹ "If you listen to my commandments...",² and "...They shall make fringes...".³ The first of these proclaims the unity of Ha-Shem and our love for Him; the second, our acceptance of all the commandments; and the third also tells us to remember all the commandments [as it says "And you shall see them (i.e., the fringes) and remember all My commandments and perform them"].⁴ In addition, the third section contains a reminder of the exodus from Egypt, as it says "I am Ha-Shem your G-d who brought you out of the land of Egypt",⁵ which we are commanded to remember, as it says "In order that you remember the day of your departure from the land of Egypt all the days of your life".^6,a A man may recite the shema in any language that he understands.^b

We recite the shema every evening and morning at the time that people lie down and at the time that they get up, as it says "And you shall speak about them... when you lie down and when you get up".^7,c Specifically, we recite it in the evening between the time the stars come out and dawn (before midnight if possible) and in the morning between dawn and the end of the first quarter of the day (but preferably just before sunrise).^d We recite two benedictions before it and one after it in the daytime; two before it and two after it at night.^e

Sources:
1. Deut. 6:4-9	a. 1:2-3
2. Deut. 11:13-21	b. 2:10
3. Num. 15:37-41	c. 1:1
4. Num. 15:39	d. 1:9-11
5. Num. 15:41	e. 1:5
6. Deut. 16:3
7. Deut. 6:7