Charles H. Spurgeon on Psalms 116:5

The first attribute, "gracious, "(Nwgx) hath especial respect to that goodness which is in God himself. The root (Ngx) whence it cometh signifieth to do a thing gratis, freely, of one's own mind and goodwill. This is that word which is used to set out the free grace and mere goodwill of God, thus (Nxa ddva ta ytgxw) "I will be gracious to whom I will be gracious, "Ex 33:19. There is also an adverb (Mgh) derived thence, which signifieth gratis, freely, as where Laban thus speaketh to Jacob, "Shouldest thou serve me for nought?" Thus is the word opposed to merit. And hereby the prophet acknowledged that the deliverance which God gave was for the Lord's own sake, upon no desert of him that was delivered.

The second attribute, "righteous" or just, (qydu), hath particular relation to the promise of God. God's righteousness largely taken is the integrity or equity of all his counsels, words, and actions... Particularly is God's righteousness manifested in giving reward and taking vengeance. Thus it is said to be "a righteous thing with God to recompense tribulation to them that trouble you; and to you who are troubled rest, "2Th 1:6-7... But the occasion of mentioning God's righteousness here in this place being to show the ground of his calling on God, and of God's delivering him, it must needs have respect to God's word and promise, and to God's truth in performing what he hath promised. William Gouge.