"What was God saying by making use of these quotations? To answer this question, You need to know two things: the context from which each passage is drawn and thew way in which the people of that time understood the passage. Both Psalm 2 and Isaiah 2 were understood as powerful messianic prophecies.
In Psalm 2, God makes a royal proclamation announcing his Son, the king of kings who would rule over the whole earth.
But in Isaiah 42, God speaks about his 'servant' (also understood to be the Messiah). Paradoxically, God's Messiah is both a king and a servant. This passage from Isaiah also proclaims that God's Spirit is upon his servant. How fitting since the Father utters these words as the Spirit descends on Jesus in the Jordan River.
The reference "whom I love" is likely drawn from Genesis 22, one of the most poignant scenes in the Old Testament. Abraham is about to sacrifice Isaac out of obedience to God. Genesis heightens the drama by emphasizing how precious Isaac is to Abraham, foreshadowing the Father's own feelings for his only Son.
When Jesus is baptized in the Jordan, the Father is saying, " Here is my precious son, my Isaac," hinting at the sacrifice he will soon ask of Jesus.
In just three brief quotes from the scriptures, God speaks of Jesus as a king, a servant, and his Son, who will become a sacrifice. When God speaks, he packs a lot into his words! And be sure to notice where these three passages come from: the Torah (Genesis 22), the Prophets (Isaiah 42), and the Psalms (Psalm 2)*. ...God links together words from the three parts of Scripture. By quoting all three, he is proclaiming that the entire scriptures point to Jesus as their fulfillment."
[ *Donna Note: The Jews divide the Old Testament into three parts Torah= The first 5 books of Moses known as The Law (these hold the most weight); the Prophets (in Hebrew, the Neviim) and the Writings (In Hebrew, the Ketuva). These form the acronym for the entire Old Testament The TaNaK (pronounced as tuh-knock).
Matt. 22:40 and many other places have an example of this: "On these two commandments hang all the law and the prophets."
Whenever Jesus says, "Is it not written?" he is always referring to scriptures. Sometimes when he says, "Ye have heard" as in Matthew 5:43, he is referring to teachings of others such as the Essenes.]
Happy Memorial Day!