(5) And ADONAI descended in the cloud, and stood with him there, and proclaimed the name of ADONAI. (6) And ADONAI passed by before him, and proclaimed: ‘ADONAI, ADONAI, God, merciful and gracious, long-suffering, and abundant in goodness and truth; (7) keeping mercy unto the thousandth generation, forgiving iniquity and transgression and sin; and that will by no means clear the guilty; visiting the iniquity of the fathers upon the children, and upon the children’s children, unto the third and unto the fourth generation.’
Tosephot to Rosh HaShanah 17b (Rabbenu Tam 1000-1071):
Adonai: The Lord is merciful before a person sins
Adonai: The Lord is merciful after a person has sinned and repented
El: He is all-powerful
rahum: He is compassionate
vehanun: and gracious
erekh appayyim: He is slow to anger
verav hesed: He is abounding in kindness
veemet: even after His scrutiny of our conduct
notzer hesed la'alafim: His kindness extends to future generations
nosei avon: He forgives sins committed willfully
vafesha: He forgives sins committed in defiance of His will
vehataah: as well as those committed unwittingly
venakkeh: He acquits the repentant sinner.
(5) you shall not bow down unto them, nor serve them; for I, ADONAI your God am a jealous God, visiting the iniquity of the fathers upon the children unto the third and fourth generation of them that hate Me; (6) and showing mercy unto the thousandth generation of them that love Me and keep My commandments.
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Rashi (Rabbi Shimon ben Yitzchak 1040-1105)
and He called out in the name of the Lord: We render: וּקְרָא בִשְׁמָא דַיְיָ, and he called out in the name of the Lord. [from Onkelos]
Lord, Lord: This is God's Attribute of Compassion. [It is repeated,] once for before the person sins, and once for after he sins and repents.
God: Heb. אֵל. This too is an attribute of compassion [for God], and so he [the Psalmist] says: “My God, my God, why have You forsaken me?” (Ps. 22:2). One cannot say to the Divine attribute of justice, “Why have You forsaken me?” I found this in the Mechilta (Exod. 15:2).
slow to anger: He puts off His anger and does not hasten to exact retribution, [hoping that] perhaps he [the sinner] will repent.
and abundant in loving-kindness: for those who need loving-kindness because they lack sufficient merits. -[from R.H. 17a]
and truth: to pay a good reward to those who do His will.