John Calvin Commentary Isaiah 37:14

"And Hezekiah received the letter from the hand of the messengers, and read it; and Hezekiah went up unto the house of Jehovah, and spread it before Jehovah." — Isaiah 37:14 (ASV)

Hezekiah took the letters. The Prophet now shows what kind of refuge Hezekiah had amid such great calamities. He immediately went into the Temple to lament before the Lord the calamity which he could not remove, and to cast upon him (Psalms 55:22) his grief and his anxieties. Nor was this a blind or confused lamentation, but the pious king wished to move God by his tears and complaints to render assistance. We are taught by his example that, when we are hard-pressed, there is nothing better than to cast our burden into the bosom of God. All other methods of relief will be of no avail if this single method is lacking.

And spread them before Jehovah. In “spreading the letters before the Lord,” he does not do this as if the Lord did not know what was contained in the letters; rather, God allows us to act in this manner toward Him, in accommodation to our weakness. Neither prayers, nor tears, nor complaints make known to God what we need, for He knows our wants and necessities before we ask anything from him (Matthew 6:8).

But here we should rather consider what is necessary for us: that is, that God should manifest that He knows the blasphemies of adversaries, and that those who have uttered them will not remain unpunished. The reason and design, therefore, why Hezekiah “spread before the Lord the letters” of the wicked tyrant was this: that he might excite his own earnestness and inflame his own ardor in prayer.