The Mishna (49b) taught that a traveler can announce that he is establishing his place for Shabbat at a certain tree that is within 2,000 amot to the city. This allows him to reach his home in the city even after Shabbat has begun. According to the Mishna, this ruling is based on the principle that “a poor man can establish an eiruv with his feet,” meaning that he does not need to place food for two meals as an eiruv if he establishes his place based on his physical presence there.
On this ruling, the Mishna brings a disagreement between Rabbi Meir, who limits it to a poor person – but a rich person would need to make his eiruv with food – and Rabbi Yehuda, who says that both rich and poor people can establish their eiruv by walking to the spot. According to Rabbi Yehuda, making an eiruv by using food is a leniency shown to the rich person, to save him the trouble of having to walk to the place of the eiruv before Shabbat.
The Rashba explains that the use of the terms “rich” and “poor” is not to be understood literally. The traveler in the Mishna is considered “poor” because he is on the road and likely does not have access to two meals worth of food. Anyone sitting at home would be considered “rich” as far as the case of the Mishna is concerned. This explanation is essential in order to explain a case brought in the Gemara by Rabbi Yehuda to prove his position.
Rabbi Yehuda said: There was an incident involving members of the household of the Memel family and members of the household of the Guryon family in the village of Aroma, who were distributing dried figs and raisins to the paupers in years of famine, and the paupers of the village of Sihin and the paupers of the village of Hananya would come to the edge of the limit at nightfall, which was also within the limit of Aroma, and then go home. The following day they would rise early and go to receive their figs and raisins. Apparently, one can establish an eiruv by foot, if he says: My residence is in my present location.
The poor who lived in the neighboring villages of Sihin and Hananya would walk to the edge of the tehum in the late afternoon on Friday, so that they would be able to walk to Aroma on morning. If we are to understand that the “poor” person under discussion was literally poor, this case would prove nothing – even Rabbi Meir agrees that poor people do not need to use food to establish their eiruv. Apparently the poor people of Shihin and Hananya who were coming from their homes were not considered poor, since they had some food at home, so their establishing their tehum by their physical presence supports Rabbi Yehuda’s position that even the “rich” can establish the eiruv in that way.