If I say... — Or, If, thought I, I should reason thus, I should be faithless to the generation of thy sons. Or, perhaps, if it ever occurred to my mind to speak thus, the Hebrew often using two finite verbs to express one thought. (See, e.g., Psalms 73:8; Psalms 73:19.)
Related Commentaries of Psalms 73:15
Psalms 73:15
15 If I say, I will speak thus; behold, I should offend against the generation of thy children.