Albert Barnes Commentary 2 Kings 20:3

"Remember now, O Jehovah, I beseech thee, how I have walked before thee in truth and with a perfect heart, and have done that which is good in thy sight. And Hezekiah wept sore." — 2 Kings 20:3 (ASV)

Remember now - The old covenant promised temporal prosperity to the righteous, including length of days. Hezekiah, conscious of his faithfulness and integrity (2 Kings 18:3–6), ventures to argue his case (compare also the note on 2 Kings 21:1). According to the highest standard of morality revealed up to that time, there was nothing improper in the king's self-vindication, which has many parallels in the Psalms of David (Psalms 7:3–10; Psalms 18:19–26; Psalms 26:1–8; etc.).