When Ya'akov Avinu requests of his son Yoseif to bury him in Eretz Yisrael, in the M'arat HaMachpeilah, he notes that he did not do the same for Yoseif's mother, Rachel Immeinu. "And I, when I came from Padan, Rachel died while still a journey away from Efrat, and I buried her there on the road to Efrat, which is Beis Lechem (VaYechi 48:7)." Rashi explains that Ya'akov's intention was to convey to Yoseif that he did so based on Divine command. Since later in Jewish history, Klal Yisrael, Rachel's descendants, would be exiled and pass by Kever Rachel, she would "go out near her grave" and cry and pray for mercy for them. This is described by the prophet, Yirmiyahu, "kol b'Ramah nishma..., Rachel m'vaka 'al baneha," "a voice is heard in Ramah, Rachel is crying for her children." Hashem assures her: "min'i koleich mibechi v'einayich mi'dim'a ki yaish sachar lif'ulaseich n'um Hashem, v'shavu mei'eretz oyaiv," "stop your voice from crying and your eyes from tears, for there is reward for your actions, says G-d, and they [your children] will return from the land of the enemy (31:15)." In light of this explanation, Yoseif would not resent Ya'akov's actions concerning the place of his mother's burial and would wholeheartedly fulfill his father's request.
Mori V'Rabi, Rav H. Schachter shlit"a, suggested that Ya'akov's comfort to Yoseif was more direct than appears at first. The benefit of being buried in the M'arat HaMachpeila is that it would serve as a makom tefila, a place of prayer, for all generations. The souls of the inhabitants therein, the Avot and Imahot would pray there (see Bava Metsi'a 85b); their descendants throughout the centuries, starting with Kaleiv (see Shelach 13:22 and Rashi there) until today would do so as well. This same benefit of being buried in a makom tefila would apply to Kever Rachel, as it too would serve as a place of prayer both for Rachel and for her children. Therefore, Yoseif would not feel resentment over the slight to his mother's honor, since her burial place would achieve the same purpose as the burial place to which Ya'akov Avinu was now requesting that his son transport him.
The tefila of Rachel is a tefila b'eis tzara, a prayer in times of need. Ramban (Hasagot l'Seifer HaMitzvot, Mitvat 'Asei 5) notes that although, in his opinion, obligatory daily prayer is Rabbinic in nature, prayer in times of tzara is min haTorah. Rambam (Hilchot Ta'aniyot 1:1), as well, while maintaining that daily prayer is a Biblical obligation, rules that tefila b'eis tzara also is a separate Torah obligation. Rambam and Ramban both indicate that such prayer demonstrates an awareness of the fact that the Almighty is in total control of he world, brought about the events leading to such heartfelt prayer, and has the supreme power to save the supplicants from the precarious situation. Rambam even notes (ibid., Halacha 3) that to do otherwise, not to cry out to G-d under such circumstances, would be "cruelty" lest such a non-believing attitude lead to additional tragedy. R. Moshe Feinstein zt"l rules (Igros Moshe O"C 2:25), based on similar logic, that non-Jews, although exempt from the mitzva of daily prayer, are obligated in tefila b'eis tzara. Since they are obligated in belief in G-d, not to pray under such circumstances would demonstrate a lack of faith and trust in Hashem.
Rabbeinu B'chaye (Parshas Toldos) even notes, based on Midrashei Chazal, that sometimes needs are deliberately orchestrated by the Master of All, in order to prod the individual or the tzibbur to a greater connection to G-d, through tefila. In turn, as a result of this renewed connection, Hashem will send the salvation.
As is true with all forms of prayer, and more so than with regard to other mitzvot, kavvana, concentration, is central to tefila in times of need (e.g. see R. Chayim Soloveitchik on Hilchos Tefila). Also in our Parsha, Ya'akov tells Yoseif that he took Sh'chem from the 'Emorites "b'charbi uv'kashti (48:22)" -- with my sword and my bow" -- which Targum Onkelos translates metaphorically as "with my prayer and my request," once again a reference to tefila b'eis tzara. R. Yitzchak Ze'ev Soloveitchik, the Brisker Rav, explains the comparison between a bow and tefila as follows. Just as the arrow shoots further when the bow is pulled more tightly, so too, the effect of the tefila will depend on the degree of kavvana.
An entire section of our davening on Mondays and Thursdays, beginning with "v'hu rachum", is devoted to tefila b'eis tzara for the entirety of Klal Yisrael in Galus. The Siddur Otzar HaTefilos notes that it contains 18 references to the name of Hashem and should be recited standing (and, according to some, silently) parallel to the eighteen blessings of the Shemoneh 'Esrei. We first offer 'avoda, the daily obligation of Divine service, and then we turn to a parallel tefila b'eis tzara. The words of the Brisker Rav should motivate us in our recitation of this central tefila, which, composed in straightforward language, can serve as a potent vehicle for each mispallel to be "shofeich sicho", to pour out his speech, before the Compassionate One on behalf of Knesset Yisrael.
A story is told that one of the great Roshei Yeshiva of Eretz Yisrael, when visiting Kever Rachel, would precede his heartfelt tefilot with the introduction (in Yiddish): "Mame Rachel, aiyer zin Chayim iz da" (Rachel Immeinu, your son Chaim is here). Once, in a troubling time for the Yishuv in Eretz Yisrael he stated: "Rachel Immeinu, Hashem tells you 'min'i koleich mibechi v'einayich mi'dim'a' -- and I, Chaim, tell you, cry, and continue to cry because we, your children sorely need your tefillos!"
In these extremely troubling times for K'lal Yisrael, and indeed the whole world, we must intensify our tefilos including the special tefilot b'eis tzara with the hope and confidence that in the words of the "v'hu rachum" prayer that Hashem will "habet na rachem na 'al am'cha beis Yisrael!", "look, have mercy on Your nation Israel!"