Charles H. Spurgeon on Psalms 140:13

Surely the righteous shall give thanks unto thy name. The former Psalm had its "surely", but this is a more pleasing one. As surely as God will slay the wicked he will save the oppressed, and fill their hearts and mouths with praises. Whoever else may be silent, the righteous will give thanks; and whatever they may suffer, the matter will end ill their living through the trial, and magnifying the Lord for his delivering grace. On earth ere long, and in heaven for ever, the pure in heart shall sing unto the Lord. How loud and sweet will be the songs of the redeemed in the millennial age, when the meek shall inherit the earth, and delight themselves in the abundance of peace! The upright shall dwell in thy presence. Thus shall they give thanks in the truest and fullest manner. This abiding before the Lord shall render to him "songs without words", and therefore all the more spiritual and true. Their living and walking with their God shall be their practical form of gratitude. Sitting down in holy peace, like children at their father's table, their joyful looks and language shall speak their high esteem and fervent love to him who has become their dwelling place. How high have we climbed in this Psalm —from being hunted by the evil man to dwelling in the divine presence; so doth faith upraise the saint from the lowest depths to heights of peaceful repose. Well might the song be studded with Selahs, or uplifters.