Verses with the word slow in the Old Testament (10 verses):

Exodus 4:10
And Moses said unto the LORD, O my LORD, I am not eloquent, neither heretofore, nor since thou hast spoken unto thy servant: but I am slow of speech, and of a slow tongue.

Nehemiah 9:17
And refused to obey, neither were mindful of thy wonders that thou didst among them; but hardened their necks, and in their rebellion appointed a captain to return to their bondage: but thou art a God ready to pardon, gracious and merciful, slow to anger, and of great kindness, and forsookest them not.

Psalms 103:8
The LORD is merciful and gracious, slow to anger, and plenteous in mercy.

Psalms 145:8
The LORD is gracious, and full of compassion; slow to anger, and of great mercy.

Proverbs 14:29
He that is slow to wrath is of great understanding: but he that is hasty of spirit exalteth folly.

Proverbs 15:18
A wrathful man stirreth up strife: but he that is slow to anger appeaseth strife.

Proverbs 16:32
He that is slow to anger is better than the mighty; and he that ruleth his spirit than he that taketh a city.

Joel 2:13
And rend your heart, and not your garments, and turn unto the LORD your God: for he is gracious and merciful, slow to anger, and of great kindness, and repenteth him of the evil.

Jonah 4:2
And he prayed unto the LORD, and said, I pray thee, O LORD, was not this my saying, when I was yet in my country? Therefore I fled before unto Tarshish: for I knew that thou art a gracious God, and merciful, slow to anger, and of great kindness, and repentest thee of the evil.

Nahum 1:3
The LORD is slow to anger, and great in power, and will not at all acquit the wicked: the LORD hath his way in the whirlwind and in the storm, and the clouds are the dust of his feet.