Bava Basra 37 - 43
Your Friend's Friend's Friend
Someone who is seen exercising possession of another person's field for three years and no protest is made by the original owner is believed to claim that he purchased the field and lost the bill of sale. If a protest was made he will not be able to make such a claim. This is true, rules the Sage Rav, even in a case where the original owner is a fugitive and there is a likelihood that he may never have heard of his field being taken over. Conversely, if the original owner registered a protest with two witnesses within this three year period, the possessor's claim is invalidated even if these witnesses were traveling to a destination far removed from the locale of the original owner and it is virtually impossible that they will personally relay the protest to him.
The logic covering both cases is based on the maxim that "Your friend has a friend and your friend's friend has a friend." We therefore assume that anything known to two witnesses, whether it is possession or protest, will inevitably reach the party affected by this information.
- Bava Basra 38b
When Even the Rich are Poor
This is the logic offered for explaining why a person pledging a gift of money to the poor people in his city may be referring to funds for a Sefer Torah which will benefit even the people of means.
A Sefer Torah, Rashbam explains, is a necessity for every Jew and it is customary for someone to refer to his fellow townsmen as poor if they lack a Sefer Torah for that is indeed abject poverty.
- Bava Basra 43a