The Lord is merciful and gracious - See the notes at Psalms 78:38. The idea here is derived evidently from Exodus 34:6-7 - that great and glorious statement of God himself in regard to his own character. Our world is a different world under that statement from what it would be if that and kindred declarations had not been made. There is here a “progression” of thought; an “advance” on the previous statements. At first the psalmist referred to his own individual experience Psalms 103:3-5; then he referred to the dealings of God toward the Hebrew people Psalms 103:6-7; and now he rises to the general contemplation of his character as it relates to all mankind. It was a characteristic of God in respect to all, that he was kind, compassionate, and forbearing.
Slow to anger - That is, patient; not soon excited; bearing much, and bearing it long. See James 5:11; compare Exodus 34:6-7.
And plenteous in mercy - Margin, “great of mercy.” The Hebrew word means “much,” or great;” and the idea is, that mercy is not manifested by him in small or stinted measure. It is rich; full; abundant; overflowing; free.