Leaving aside the historical concepts that inform the structure and pattern of the covenant in terms of the Hittite Suzerainty Treaties (background materials from the era), the clear message throughout the Old Testament is upon a handful of themes and they intertwine with the concept and the action of love on the part of both God and humans, specifically Israel.
The first is that God is the author and the initiator of the covenant. Regardless of which documentary source we are dealing with, the thread of “covenant” begins already, read back into the creation covenants of the Primeval History (Genesis 1-11). From Abraham on, the theme is clear: God is in charge and initiates the covenant (see Genesis 12).
The second theme is election. It should be clear from the first theme that if there is to be a covenant initiated by God, then God must choose someone to be the recipient and responder to the covenant. That someone is Israel (Deuteronomy 7:6-8). A sub-theme here is that Israel is not chosen because of any righteousness or goodness that Israel possesses. We customarily think of people who have some special quality being chosen for tasks. This is not true of Israel, and that stress maintains the sovereignty of God.
Several points might be stressed here: God exists before Israel. This is no small thing. In much of the ANE gods and peoples arose at the same time, one serving the other. For Israel God is eternal, existing before the people. This means that God could exist without Israel, and in fact God could reject Israel if the covenant does not hold. The creation stories are interwoven into the fabric of the OT in part to demonstrate God’s eternal existence before Israel comes on the scene in the early persons of Abraham and Sarah. Lastly, it means that God’s demands upon Israel are different from the demands placed on other nations by their gods. This shows up as the covenantal idea develops from Exodus to Deuteronomy. In Exodus we are dealing with a God among other gods (henotheism or monolatry) who makes ordinary demands upon a people as in the Code of Hammurabi, a document from the same time comparable to the Book of the Covenant, promulgated by the King. In Deuteronomy we get specific commands connected to ritual (Dt. 16:1-7) and food purity (Dt. 14:1-21), and relationships between people are based on models of reciprocity that derive from a covenantal concept (e.g. Dt. 23:3-7, 19).
The relationship between God and Israel in the covenant is defined as chesed חסד. The word means firmness, stability, faithfulness, or what one older scholar called leal-love, meaning a combination of loyalty and love. The word is totally connected to the covenant concept on both sides, God and Israel. Words which have a ch ח at the beginning consonant derive from an idea of keenness, sharpness – think “cutting.” There is a sharp edge to this word, so to speak; there is a sense of zeal or jealousy contained in the word. God is a jealous God (Exodus 20:5, Dt. 4:4), and yet at the same time a loving one, specifically toward Israel in the covenant relationship. It was often translated in older English Bibles as “loving-kindness” or “tender mercy,” neither of which catch the intensity of the original Hebrew.
Israelites who observe the covenant and keep the mitzvah – מצוה are known as Hasidim- see Psalm 1 and 19. A mitzvah is often translated as “commandment;” I prefer to see a mitzvah as one of many invitations God makes to enable people to express their kindness within the covenant. It is, for examples, a mitzvah to have children, to observe the Sabbath, to eat whatever is set before you when you are at another person’s table, or to provide someone with an interest-free loan. A mitzvah enables you to repair the world just a little bit. You may call it an act of charity if you wish, but make sure you keep it connected to the covenant. As one of my Jewish friends long ago said, “We don’t have to keep the commandments. We get to keep them! They are how we show our love for God.”
Israel knows God; this is the heart of the chesed Israel demonstrates. But this knowing is not merely intellectual; in Hebrew thought, knowledge is participation in the other, a deep intimacy that is shown by the fact that the same word is used to describe sexual intercourse. Israel’s knowledge of God is an intimacy such as exists between lovers. This is manifest in the book of the prophet Hosea in particular.
The other major word for love in the OT is אהבה – ahabhah – whose root means “to burn, set on fire.” The word is unique to Hebrew out of all the Semitic languages. It is a broader concept than chesed, because it indicates God’s overarching love for the whole creation and all that is within it, whereas chesed as we noted above refers to the special and intimate relationship God has with Israel – “you alone have I known out of all the nations of the world.”
When the word ahabhah is used of the love-relationship Israel has to God, however, it has an overtone of duty and commitment; it is conditioned because it is enjoined upon Israel: “Love (ahabhah) the Lord your God with all your heart and with all your soul and with all your might” (Deuteronomy 6:5). The heart is the seat of our emotions but in Hebrew thought also the seat of thought and our spiritual life. The soul (nephesh) is that which is given by God; it is what we become when the breath of life inspires us (Gen. 2:7). Without it we would not exist, so we are returning to God that which is his (this is at the heart of the Hebrew concept of sacrifice). The love exhibited by your might – מאוד – m’oth – means your physical strength, though in some Bibles it is translated as “mind.” The Greek LXX uses dynamis, an accurate rendition of the Hebrew for “strength.” The mind is more than the organ of intelligence for Hebrew thought, it is not static but always in motion, dynamic and procedural. The love of the mind is intentional, willful, and expansive as we come into contact with God. The three injunctions, taken as a unity, mean to love God with the totality of your being.