Psalms 18:1

I will love thee, O Lord - This verse is not found in the song in 2 Samuel 22. It appears to have been added after the first composition of the psalm, either by David as expressive of his ardent love for the Lord in view of his merciful interpositions in his behalf, and on the most careful and most mature review of those mercies, or by the collector of the Psalms when they were adapted to purposes of public worship, as a proper commencement of the psalm - expressive of the feeling which the general tenor of the psalm was fitted to inspire. It is impossible now to determine by whom it was added; but no one can doubt that it is a proper commencement of a psalm that is designed to recount so many mercies. It is the feeling which all should have when they recall the goodness of God to them in their past lives.

My strength - The source of my strength, or from whom all my strength is derived. So Psalms 27:1, “The Lord is the strength of my life.” Psalms 28:8, “he is the saving strength of his anointed.” Compare Psalms 29:11; Psalms 46:1; Psalms 73:26; Psalms 81:1; Psalms 140:7.