L’chatchilah, one should be strict, like the opinion of the Magen Avraham, not to walk within the entire four amot before a person reciting the Amidah. In times of need, however, one may be lenient like the Eliyah Rabbah and permit passing beside a person praying, and likewise passing and standing directly in front of his face.
In a case of great need, when there is no other choice, it is even permissible to pass directly in front of a person reciting the Amidah. For instance, in order to complete a minyan it is permitted to pass in front of someone who is praying. It is permissible for one who must conduct a Torah class, and for a Kohen who must ascend to recite Birkat Kohanim, to pass in front of the person praying. Likewise, whoever fears he will miss his bus or ride is permitted to pass as well.
However, one who arrives late to the prayer service and wants to pray in his regular seat is prohibited from passing in front of the person reciting the Amidah. If only one person is reciting the Amidah where he must pass, he may rely on the Eliyah Rabbah and pass beside him. Yet, if in order to do so he must pass alongside a number of people praying, he may not pass, since it is almost certain that he will disturb at least someone’s concentration.
If a person is reciting the Amidah while standing in an aisle, since he did not act in accordance with the law by standing in a place that blocks the walkway of those coming and going, there is no obligation to take him into consideration, and in times of need, it is permitted to pass before his face.
. The majority of poskim, Rishonim and Acharonim alike, are of the same opinion as that of the Eliyah Rabbah, as explained in the book Four Amot of Prayer, p. 338. This is also the simple meaning of the words in the Talmud, “It is prohibited to pass in front of the people praying.” Therefore, despite the fact that l’chatchilah it is good to follow the Magen Avraham, in times of need it is possible to rely on the opinion of the Eliyah Rabbah. In general, it is possible to explain the opinion of the Eliyah Rabbah, that the prohibition to pass is only when it causes a great distraction to a person reciting the Amidah. A great distraction is only one in which a person crosses over the four amot in front of the face of the person who is praying, or if the person praying in front of him finishes his prayer and steps backwards directly in front of him. According to the Magen Avraham 102:6, the prohibition also applies when there is even a small distraction.The Magen Avraham 102:5 writes further, in the name of the Zohar, that one should be more stringent, that even on the sides of one reciting the Amidah it is prohibited to pass. The reason is that this is considered a holy place, and not just because of the disturbance it causes. Some Acharonim write that it is correct to be stringent and act according to the Zohar’s opinion, as the Kaf HaChaim 102:27 writes, and as is implied from the Mishnah Berurah 17 (although Aruch HaShulchan 102:12 explains the Zohar in a way that agrees with the Talmud).
By contrast, the Eshel Avraham Butshatsh is very lenient regarding this law and maintains that the whole prohibition depends on the extent of the disturbance caused to the person reciting the Amidah. Therefore, if his eyes are closed, it is permissible to pass. Likewise, if he is reciting the prayers of supplication at the end of the Amidah, it is permissible to pass by him (and concerning this ruling the Aruch HaShulchan 102:13 agrees, although many poskim disagree with them). The Eshel Avraham writes further, that in times of need, it is permitted to pass before the person praying, since perhaps he is reciting the prayers of supplication, and we are lenient regarding an uncertainty surrounding a rabbinic obligation. Moreover, he writes that for a mitzvah, it is permissible to pass before the person praying.
In order to complete a minyan, Yad Eliyahu 6 writes that it is permitted to pass in front of a person reciting the Amidah. However, in order to pray with the minyan it is not allowed. Magen Avraham 69:4, cited by the Mishnah Berurah 69:9, writes that one may not pass in front of a person praying in order to respond to Barchu. Eshel Avraham permits passing in order to respond to Kaddish and Barchu, and to pray with a minyan. Further, the Eshel Avraham writes that in order not to transgress the prohibition of “Do not abominate oneself” (as when one needs to go to the restroom), one is allowed to pass in front of a person praying (and it seems that in this matter all poskim are in agreement). Concerning their dissension, since it is a rabbinic doubt, although the lenient poskim are but a few, in times of need, it is permissible to rely on them. Also, Avnei Yashfeh 7:22 relies on the opinion of the Eshel Avraham in that he permits passing before a person reciting the Amidah in order to pray with a minyan and to hear Kaddish. He adds another reason, that today the kavanah in our prayers is minimal and the person passing does not greatly disturb. However, he forbids passing in order for someone to pray in his regular seat. Based on logical reasoning, I wrote that it is permissible to pass by the side of the person praying in order to get to one’s permanent place of prayer but that it is forbidden to pass by the sides of a few people, because he will certainly disturb one of them, which is also how I have seen people practice.