After revealing his identity to his brothers and telling them to return to Eretz Canaan and to bring their father Yaakov back with them to Egypt, Yosef instructs his brothers not to become agitated along the way (Bereishit 45:24). One interpretation of this instruction, presented by Rashi there (s.v. al tirgezu), is that they shouldn’t do anything which will endanger themselves during their journey. The Yerushalmi in Berachot (4:4, 34b) indicates that roads on which people travel are generally places of danger, while the Yerushalmi in Shabbat (2:6, 19b) states similarly that one who is traveling is subjected to a greater likelihood of danger than one who is at home, thereby explaining why Yaakov was initially so adamantly opposed to allowing Binyamin to go down to Egypt with his brothers (see Bereishit 42:38).

The Gemara in Berachot (29b) records that Eliyahu HaNavi once appeared to one of the Amoraim and told him that before setting out on a journey, it is proper to ask permission from Hashem to leave (see Rashi there, s.v. himalech). The Gemara then states that this is a reference to Tefillat HaDerech, the traveler’s prayer, and outlines the text of this prayer, which includes a request for protection from any potential danger along the way. In a subsequent passage there (30a), the Gemara asks exactly when this prayer should be recited, meaning, at what point in the journey, and responds that one should say it right when setting out on the road. Finally, the Gemara indicates that the prayer is to be recited upon traveling the distance of a parsah, the equivalent of eight thousand Amot (about twelve to sixteen thousand feet, or about two and a third to three miles).

Rashi there (s.v. ad parsah) presents two understandings of this last point. First, he says that the Gemara means to rule that one must recite Tefillat HaDerech while still within the first parsah of his journey, but once he has traveled beyond that distance, he may no longer say it because, as noted by the Meiri (Beit HaBechirah to Berachot 29b, s.v. kol hayotzei), one cannot be considered as “asking permission of Hashem to leave,” the stated purpose of this prayer, once he has already traveled so far. Rashi then cites the Bahag, however, who holds that the Gemara’s intent is to teach that in order for one to become obligated to recite Tefillat HaDerech, the total distance of his journey must be at least one parsah;, that is, he must be traveling a significant distance. If he is, though, he may recite the prayer at any time during the trip, even after covering the distance of a parsah. The Rosh in Berachot (4:18) concurs with the position of the Bahag, but adds that if one did not say Tefillat HaDerech and has reached to within one parsah of his destination, he may no longer say it at that point.

The Shulchan Aruch (Orach Chaim 110:7) rules that one recites Tefillat HaDerech upon setting out on his journey; the Magen Avraham (ibid. No. 14) points out, though, that one should wait until he has traveled beyond the city limits, defined according to halachah as when there is a break in continuous houses of more than 140 2/3 Amot, or about 211 to 281 feet. The Taz (ibid. No. 6), however, disagrees and asserts that one may say Tefillat HaDerech even before leaving town, as long as he has decided that he is definitely traveling and has prepared to do so; he notes that the Maharam MiRuttenburg, as quoted in the Shulchan Aruch (ibid. No. 6), would recite Tefillat HaDerech as part of his morning davening. The Mishnah Berurah (ibid. No. 29) reports that most authorities nonetheless accept the former position, that one should wait until he is beyond the city line, but he adds that this is true only when one is leaving one’s initial point of departure. If, however, one is traveling for several days and sleeping overnight on the road, in which case, as the Mishnah Berurah points out earlier (ibid. No. 26; see Biur Halachah s.v. tzarich), a new Tefillat HaDerech must be said each day when he sets out on his way again, he need not wait until leaving the city limits of the place in which he stayed temporarily, but may rather say the prayer immediately upon departing.

As for the two opinions about the meaning of the statement that Tefillat HaDerech is to be recited upon traveling the distance of a parsah, the Shulchan Aruch (ibid. No.7) rules in accordance with the Bahag that one says this prayer only if traveling at least that far, not that one must necessarily say it within the first parsah of his trip. If, therefore, one did not say Tefillat HaDerech towards the beginning of his trip, he may say it at any time, until he is within a parsah of the city of his final destination, at which point, as noted by the Mishnah Berurah (ibid. No. 30), one may assume that there is no longer any danger (although he adds that if one is aware of a specific danger, he may say the prayer even then). The Rama (ibid.), however, acknowledges the view of Rashi, and writes that it is indeed preferable to say Tefillat HaDerech before having traveled the distance of a parsah.

The question is how exactly to understand what is meant by a parsah in connection with this halachah, specifically, whether it is a matter of distance or of time. According to the calculations of the Gemara in Pesachim (93b-94a), a parsah is the equivalent of four Mil (see Mishnah Berurah ibid. No. 31); although this is a measure of distance, the Gemara there relates it to the amount of time it takes the average person to cover that distance when walking on foot. Three different possibilities emerge from that Gemara as to exactly how much time is represented by a Mil; see the discussion in the Biur HaGra to Orach Chaim 459 s.v. veshiur, the Chok Yaakov (ibid. No. 10), and the Mishnah Berurah (ibid. No. 15, with the Biur Halachah s.v. hevei), among other sources. The most widely accepted view is that a Mil can be walked in eighteen minutes; four Mil, then, or a parsah, represents seventy two minutes. Regarding the obligation of Tefillat HaDerech, then, must the journey be at least one parsah in length or at least seventy minutes in length? The difference, of course, relates to how one is traveling; one who travels by car, and certainly by train or by plane, covers the distance of a parsah in a matter of a few moments. Is that still the standard in terms of the length of the trip which requires Tefillat HaDerech nonetheless, or should the length of the trip be measured in terms of time, meaning that Tefillat HaDerech would be required only if one will be traveling for at least seventy two minutes, regardless of the mode of transportation, and hence regardless of how much distance he covers.

This question is subject to dispute; the Mishnah Berurah (ibid. 110:30) accepts the former position and thus rules that one who travels by train should recite Tefillat HaDerech even if he is traveling only the distance of a parsah (beyond the city limits, as explained above), a relatively short trip, and that he should say it right upon his departure so as to follow the aforementioned position of Rashi. This opinion is accepted by many others as well; see, for example, the Minchas Elazar of Munkatch in his Nimukei Orach Chaim (110:5) and Rav Shlomo Zalman Auerbach, cited in Halichot Shlomo on Tefillah, Chapter 21, Devar Halachah No. 7). Rav Yechiel Zilber, in Shu”t Az Nidberu (6:66), explains that since Tefillat HaDerech relates, as noted above, to whatever dangers are present when traveling some distance outside city limits, the requirement to recite it applies even if that distance is covered with greater speed. Rav Ovadyah Yosef (Shu”t Yabia Omer Volume 1, Orach Chaim No. 13 and Volume 6, Orach Chaim No. 48), however, sides with those who disagree and maintain that one does not recite Tefillat HaDerech if the trip is less than seventy two minutes in length. The She’arim Metzuyanim BeHalachah to the Kitzur Shulchan Aruch (68:2) concurs with this view, and notes that the Mishnah Berurah elsewhere, regarding another halachah (Biur Halachah to Orach Chaim 163:1, s.v. berichuk) rules that the mode of travel does indeed matter, as the issue to consider is time and not distance (see also Mishnah Berurah to Orach Chaim 240:1 and 249:1).

There is some question regarding whether or not Tefillat HaDerech is required when flying in a plane at all, as one is not then traveling along “roads” in the classic sense. The Rogatchover Gaon, cited by Rav Shlomo Zevin in his Ishim VeShittot (page 97), suggested based on a Gemara in Chullin (139b) that it is not. Rav Ovadyah Yosef (Shu”t Yechaveh Da’at 2:26), however, appears to disagree (see also Shu”t Sho’el U’Meishiv I:3:103 regarding travel in a hot air balloon), and the contemporary practice is that Tefillat HaDerech is indeed recited when traveling by air. It may perhaps be added that since the danger of the voyage is a motivating factor behind the obligation to recite this prayer, it should certainly apply to air travel as well. It is noteworthy, in this vein, that Rav Moshe Shternbuch (Shu”t Teshuvot VeHanhagot 1:199) cites from the Chazon Ish that given the number of automobile accidents that occur regularly, even close to home, the recital of Tefillat HaDerech should theoretically be mandated whenever one travels by car, even within the city limits, but that did not become the accepted practice.