Therefore - לכן lākên, “certainly, truly.” In view of what has been just said. Or perhaps the word means merely certainly, truly.
Do my thoughts cause me to answer - This is variously rendered. The Vulgate renders it, Idcirco cogitationes meae variae succedunt sibi, et mens in diversa rapitur - “Therefore my various thoughts follow in succession, and the mind is distracted.” The Septuagint, “I did not suppose that thou wouldst speak against these things, and you do not understand more than I.” How this was ever made from the Hebrew it is impossible to say. On the word “thoughts,” see the notes at Job 4:13. The word denotes thoughts which divide and distract the mind; not calm and collected reflections, but those which disturb, disconcert, and trouble. He acknowledges that it was not calm reflection which induced him to reply, but the agitating emotions produced by the speech of Job. The word rendered “cause me to answer” (ישׁיבוּני yeshı̂ybûnı̂y), “cause me to return” - and Jerome understood it as meaning that his thoughts returned upon him in quick and troublesome succession, and says in his Commentary on Job, that the meaning is, “I am troubled and agitated because you say that you sustain these evils from God without cause, when nothing evil ought to be suspected of God.”
And for this I make haste - Margin, “my haste is in me.” The meaning is, “the impetuosity of my feelings urges me on. I reply on account of the agitation of my soul, which will admit of no delay.” His heart was full, and he hastened to give vent to his feelings in impassioned and earnest language.