Charles H. Spurgeon on Psalms 106:31

And that was counted unto him for righteousness unto all generations for evermore. Down to the moment when this psalm was penned the house of Phinehas was honoured in Israel. His faith had performed a valorous deed, and his righteousness was testified of the Lord, and honoured by the continuance of his family in the priesthood. He was impelled by motives that what would otherwise have been a deed of blood was justified in the sight of God; nay, more, was made the evidence that Phinehas was righteous. No personal ambition, or private revenge, or selfish passion, or even fanatical bigotry, inspired the man of God, but zeal for God, indignation at open filthiness, and true patriotism urged him on. Once again we have cause to note the mercy of God that even when his warrant was out, and actual execution was proceeding, he stayed his hand at the suit of one man: finding, as it were, an apology for his grace when justice seemed to demand immediate vengeance.