Charles H. Spurgeon on Psalms 135:5

For I know. The word "I" is made emphatic in the original. Whatever may be the case with others, I have had personal and precious experience of the greatness of Jehovah's power, and of his infinite supremacy above all other gods. The author of the Psalm may either speak for all Israel as a unit, or he may have framed his song so that every worshipper might say this for himself as his own testimony. —Henry Cowles.