Keva vs. Kavanah (Set [Rote] vs. Mindful Tefillah) :

Tractate Berakhot 3a
Rav Yitzḥak bar Shmuel said” in the name of Rav: The night consists of three watches, and over each and every watch the Holy One, Blessed be He sits and roars like a lion, [because the Temple service was connected to the changing of these watches (Tosefot HaRosh)] and says: “Woe to Me, that due to their sins I destroyed My house, burned My Temple and exiled them among the nations of the world.

Incidental to the mention of the elevated significance of the night watches, the Gemara cites a related story: It was taught in a baraita that Rabbi Yosei said: I was once walking along the road when I entered the ruins of an old, abandoned building among the ruins of Jerusalem in order to pray. I noticed that Elijah, of blessed memory, came and guarded the entrance for me and waited at the entrance until I finished my prayer. When I finished prayingand exited the ruin, Elijah said to me, deferentially as one would address a Rabbi: Greetings to you, my Rabbi. I answered him: Greetings to you, my Rabbi, my teacher. And Elijah said to me: My son, why did you enter this ruin? I said to him: In order to pray. And Elijah said to me: You should have prayed on the road. And I said to him: I was unable to pray along the road, because I was afraid that I might be interrupted by travelers and would be unable to focus. Elijah said to me: You should have recited the abbreviated prayer instituted for just such circumstances.

Rabbi Yosei concluded: At that time, from that brief exchange, I learned from him, three things: I learned that one may not enter a ruin; and I learnedthat one need not enter a building to pray, but he may pray along the road; and I learned that one who prays along the road recites an abbreviated prayer so that he may maintain his focus.

And after this introduction, Elijah said to me: What voice did you hear in that ruin?
I responded: I heard a Heavenly voice, like an echo of that roar of the Holy One, Blessed be He (Maharsha), cooing like a dove and saying: Woe to the children, due to whose sins I destroyed My house, burned My Temple, and exiled them among the nations.

And Elijah said to me: By your life and by your head, not only did that voice cry out in that moment, but it cries out three times each and every day. Moreover, any time that God’s greatness is evoked, such as when Israel enters synagogues and study halls and answers in the kaddish prayer, May His great name be blessed, the Holy One, Blessed be He, shakes His head and says: Happy is the king who is thus praised in his house. When the Temple stood, this praise was recited there, but now: How great is the pain of the father who exiled his children, and woe to the children who were exiled from their father’s table, as their pain only adds to that of their father (Rabbi Shem Tov ibn Shaprut).

When a person is in distress and has no time to recite the Amidah, which contains nineteen berachot, he can recite a short prayer that includes the first three berachot and the last three blessings. The middle berachah begins with the word 'הביננו', and is the summary of the thirteen central berachot, as the Rambam says:
"... but if he was preoccupied or distressed, or short of his tongue, he prayed three first berachot and one berachשי of all the middle ones and three last blessings and fulfilled his duty." (Mishneh Torah, Sefer Ahava, Laws of Prayer and Birkat Kohanim 2: 2)
In the rainy days and in the origin of the Shabbat and festivals, this prayer is not recited, but the entire Amida prayer.

"Give us wisdom, Lord our God to know Your ways

And turn our hearts to fear You
And forgive us that we may be redeemed

And distance us from hurt,
And nourish us in the fertile fields of Your land,
And gather the dispersed from the four,

dispersion from four will be gathered,
And judge those who stray,

And lift your hand to the evil ones,

And [That] the righteous shall rejoice in the building of your city and the repair of your sanctuary,

And the growth of the horn [glory] of David Your servant

And the lighting of the candle for the son of Yishai your annointed one.

Before You are called upon You answer. Blessed are the Lord, who hears the Tefillah".