Charles H. Spurgeon on Psalms 108:7

God hath spoken the word of assurance. This refers to all the words in which the land of their inheritance was defined, especially Ge 15:18 Ex 23:31 De 11:24, and that remarkable prediction concerning the perpetuity of David's line, 2Sa 7:1-17, which must have made a deep impression on his mind. From these passages it is evident that Aram as well as Edom was included in the full compass of the territory designed for Israel, and that David felt himself to be in the path of destiny when he was endeavouring to extend his sway from the river of Egypt to the great river, even the Euphrates. In his holiness, in the immutable integrity of his heart, which was an infallible guarantee for the fulfilment of his promise. I will exult. This is the exclamation of the representative head of the people, when he ponders upon the divine utterance. —James G. Murphy.