Question: Must one join one’s feet together during the Amida prayer? Similarly, if one prays while sitting, has he fulfilled his obligation?
Answer: Before one begins the Amida prayer, one must join both feet together as if they were one foot in order to compare ourselves to the angels about whom the verse (Yechezkel 1, 7) states, “And their feet are a straight foot,” meaning that their feet appear like one foot.
One’s feet must be joined together completely, both at the heels and at the front of the feet where the toes are. Nevertheless, some Acharonim write that it is sufficient if the feet are joined together at the heels and there is no prohibition for the front of the feet where the toes are not to be touching. The Poskim therefore rule that one who does not join one’s feet at the front of the foot has on whom to rely. There are indeed certain Torah scholars who follow this custom. Nevertheless, it is preferable to join one’s feet throughout the entire length of the foot in order to completely resemble the angels whose feet look like only one foot.
One must recite the Amida prayer while standing. If one prayed while sitting, according to most Poskim, one must repeat the Amida while standing. The same applies to one who has prayed while sitting because he had no other choice, such as if one was quite ill and his situation later improved to the extent where he is capable of standing up and praying again (for instance, a diabetic who was feeling weak and a short time later feels much better), that according to most Poskim, this individual is obligated to stand up and pray again in order to fulfill his obligation.
Nevertheless, since there are Poskim who rule that one need not repeat the Amida while standing once one has already prayed while seated, for one has already fulfilled his obligation even while seated, Maran Rabbeinu Ovadia Yosef zt”l rules (in Yalkut Yosef, Volume 1) that one who has prayed while seated, such as an ill individual who now feels better, should stand up and pray again but only as a “conditional, donated prayer.” This means that before one begins to pray, one should say verbally, “I am hereby standing and reciting the Amida prayer once again in order to fulfill my obligation according to the Poskim who rule that I am obligated to do so. If the Halacha does not follow these Poskim, I hereby intend for this prayer to be a donated prayer (an optional prayer one can “donate” to Hashem).”
In this way, one fulfills his obligation according to all opinions, for if one is obligated to stand up and pray again, one is doing so and if not, one is praying an optional, donated prayer, which is also permissible.
Similarly, if one is travelling on a train and realizes that the time for prayer will soon pass and he cannot pray while standing so he prayed while seated and later got off the train and realizes that the time for prayer has not yet passed, one must likewise repeat the Amida prayer while standing albeit as a “conditional, donated prayer” as we have delineated above.
Regarding prayer on an airplane, on long flights, there are sometimes those who arrange a Minyan for prayer. When Maran zt”l would fly from Israel to New York, some people suggested that they organize a Minyan on the plane, but Maran zt”l told them that it is better for every individual to pray alone at his own seat as opposed to organizing a Minyan in the back of the plane and interfering with the flight crew and their work. (Note: Nevertheless, regarding the Amida prayer regarding which we have written that according to most Poskim, one must recite it standing in order to fulfill one’s obligation, there is sometimes not enough room at one’s own seat to remain standing for too long. There are possibilities for one to pray alone on an airplane while standing in places where it does not bother any crew members or passengers, such as at emergency exits and the like. One should, nevertheless, always exercise good judgment before doing so by taking one’s surroundings into consideration.)