Charles H. Spurgeon on Psalms 103:9

He will not always chide. He will sometimes, for he cannot endure that his people should harbour sin in their hearts, but not for ever will he chasten them; as soon as they turn to him and forsake their evil ways he will end the quarrel. He might find constant cause for striving with us, for we have always something in us which is contrary to his holy mind, but he refrains himself lest our spirits should fail before him. It will be profitable for any one of us who may be at this time out of conscious fellowship with the Lord, to inquire at his hands the reason for his anger, saying, "Shew me wherefore thou contendest with me?" For he is easily entreated of, and soon ceaseth from his wrath. When his children turn from their sins he soon turns from his chidings. Neither will he keep his anger for ever. He bears no grudges. The Lord would not have his people harbour resentments, and in his own course of action he sets them a grand example. When the Lord has chastened his child he has done with his anger: he is not punishing as a judge, else might his wrath burn on, but he is acting as a father, and, therefore, after a few blows he ends the matter, and presses his beloved one to his bosom as if nothing had happened; or if the offence lies too deep in the offender's nature to be thus overcome, he continues to correct, but he never ceases to love, and he does not suffer his anger with his people to pass into the next world, but receives his erring child into his glory.