Midrasch zu Könige II 20:1

Law: A Jewish person who does not pray the morning prayer, or the Musaf prayer, or the afternoon prayer, many times; that he didn't have time for prayer, or he abridged it to take care of his [toilet] needs, or he had traveled and forgot to pray: Which time is permitted for him to pray and fulfill his obligation? What is he required to do? So taught the sages: The morning prayer is til midday, the afternoon prayer til nightfall, evening prayer has no fixed [time]. But for the Musaf [prayers], all day. Rabbi Elazar said: [If] he forgot and did not pray the Musaf prayer, and he came to pray the afternoon prayer, he should pray the afternoon prayer and afterward the Musaf prayer. Why? For everything was created for its time. The evening prayer has no fixed [time], until dawn. Why? As it is written, (Proverbs 8:17), "I love those who love me and those who seek me find me." And all those who pray and set their hearts [in concentration] for prayer, it is a good sign that his prayer is accepted, as it says, (Psalms 10:17) "You hear the desire of the afflicted..." Great is prayer before the Holy One, blessed be He. Rabbi Elazar said, "Do you want to know the power of prayer? If it does not accomplish the whole [request], it accomplishes half of it. [To illustrate, when] Cain overtook his brother Abel and murdered him, a [divine] decree went out, (Genesis 4:12) 'You will be a restless wanderer (na v'nad) on earth.' Immediately, he stood and confessed before the Holy One, blessed be He, as it says, (Genesis 4:13) 'My punishment is more than one can bear.' He said before Him: Master of the World! You bear the whole world, yet my sin You cannot bear? You wrote, (Micah 7:18) 'Who bears sin and forgives the transgression,' forgiving the great sinner. Immediately, he found kindness before the Holy One, blessed be He, and He held back the "restlessness" (na), half the decree, and so it is written (Genesis 4:16) 'And he dwelled in the land of Nod [wandering, but not na, restlessness]. From here you learn that prayer is held great before the Holy One, blessed be He. And so for Hezekiah, when He told him, (II Kings 20:1) 'Put your house in order, because you are going to die...' immediately (II Kings 20:2) 'Hezekiah turned his face to the wall [and prayed to God]...' The Holy One, blessed be He, said to him: (II Kings 20:5-6) 'I have heard your prayer... I have added 15 years for your life...' So is it written, (Psalms 145:19) 'He fulfills the desires of those who fear him; he hears their cry and saves them.'"

It is essential that a man rise early to pray, for there is nothing more powerful than prayer. A proof of this is that though at first it was decreed that Moses was not to enter or even see the Holy Land, yet because he prayed for a long time, it is written concerning him: The Lord showed him all the Land (Deut. 34:1). Similarly, because Hezekiah prayed, the decree against him was abrogated.⁹Hezekiah averted a decree of death for his failure to marry and beget children by reciting prayers (see II Kings 20:1–7, Isa. 38:1–8). And Jacob also prayed for his sons when he sent them to Egypt, as it is said:; And God Almighty give you mercy (Gen. 43:14).

Variantly: "And the L-rd said to me: 'rav lach'" (i.e., you are a "teacher" in this thing) — You are an example for judges to say: If the great sage, Moses, was not forgiven for saying (Bamidbar 20:10) "Hear, now, you rebels," but it was decreed that he not enter Eretz Yisrael, then those who delay judgment and those who pervert justice, how much more so! And if Moses who was told (Ibid. 12) "You shall not bring this congregation into the land," did not refrain from imploring the L-rd for mercy — how much more so (should this be the pattern for) other men, (who were not told such a thing!) And if Chezkiah, who was told (II Kings 20:1) "Set your house in order, for you shall die and not live" did not refrain from imploring the L-rd for mercy, acting on the principle of "Even if a sharp sword is poised over a man's neck he should not refrain from imploring mercy," as it is written (Isaiah 38:2) "then Chizkiyahu turned his face to the wall and prayed to the L-rd" — how much more so other men!