DEUT205 Duties of the heart in Scripture. When it became clear to me that, according to the dictates of reason, the [duties of the heart] should be obligatory, I said to myself: Perhaps they are not mentioned in the Torah, and that is why no one has ever written a book about them to familiarize us with the subject and reveal its principles. But when I searched for them in the Torah, I found them mentioned many times; for example: Love Hashem your God with all your heart and with all your soul and with all your might. These words which I command you this day must be on your heart (Devarim 6:5-6); To love Hashem your God, to obey His voice, and to attach yourself to Him (ibid. 30:20); To love Hashem your God and serve Him with all your heart and with all your soul (ibid. 11:13); After Hashem your God should you walk, and Him should you fear (ibid. 13:5); Love your neighbor like yourself (Vayikra 19:18); And now, Israel, what does Hashem your God ask of you? Only that you fear God (Devarim 10:12); You must love the stranger, for you were strangers in the land of Egypt (ibid. 10:19). Fear and love are among the duties of the heart. Examples of restrictive duties of the heart are: Do not desire your neighbor’s wife. Do not desire your neighbor’s house, his field, his manservant, his maidservant, his ox, his donkey, or anything that belongs to your neighbor (ibid. 5:18); Do not take revenge or bear a grudge against the children of your people (Vayikra 19:18); Do not hate your brother in your heart (ibid. 19:17); Do not stray after your heart and eyes (Bamidbar 15:39); Do not be hard-hearted or tightfisted (Devarim 15:7). There are many more passages like this. Finally, all of the service of God is reduced to that of the heart and tongue, as it is written: “For this commandment which I command you this day is neither beyond you nor far off. It is not in heaven, that you should say, ‘Who will go up to heaven for us and bring it to us, so that we can hear it and do it? ‘Neither is it across the sea, that you should say, ‘Who will cross the sea for us and bring it to us, so that we can hear it and do it?’ Rather, it is a thing very close to you, in your mouth and in your heart, that you can do” (ibid. 30:11-14).