[QUOTE=Exodus 34:4-7]
So Moses chiseled out two stone tablets like the first ones and went up Mount Sinai early in the morning, as the LORD had commanded him; and he carried the two stone tablets in his hands. Then the LORD came down in the cloud and stood there with him and proclaimed his name, the LORD. And he passed in front of Moses, proclaiming, “The LORD, the LORD, the compassionate and gracious God, slow to anger, abounding in love and faithfulness, maintaining love to thousands, and forgiving wickedness, rebellion and sin. Yet he does not leave the guilty unpunished; he punishes the children and their children for the sin of the fathers to the third and fourth generation.”
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[QUOTE=Psalm 103:8-13]
The LORD is compassionate and gracious,
slow to anger, abounding in love.
He will not always accuse,
nor will he harbor his anger forever;
he does not treat us as our sins deserve
or repay us according to our iniquities.
For as high as the heavens are above the earth,
so great is his love for those who fear him;
as far as the east is from the west,
so far has he removed our transgressions from us.
As a father has compassion on his children,
so the LORD has compassion on those who fear him;
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[QUOTE=Exodus 22:26-27]
If you take your neighbor’s cloak as a pledge, return it to him by sunset, because his cloak is the only covering he has for his body. What else will he sleep in? When he cries out to me, I will hear, for I am compassionate.
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among others. (bolding mine)
From my searching, and my knowledge of the Bible, though I’m no expert, I’d say that the most often cited characteristics showing the compassion of God in the Old Testament are
- being “slow to anger” and willing to forgive those who repent and change their evil ways
- being on the side of the poor and oppressed
- providing for and defending his people (i.e. the Israelites)