On Shabbat, a person forgot to tithe produce purchased from an unreliable seller. What may he do?
Due to the awe of Shabbat, we rely on an unreliable person's word for that Shabbat alone — even if another unreliable person vouches for it (Halachah 1). This is a leniency based on the reverence people feel toward the day.
Question 2
After relying on an unreliable person's word on Shabbat, what must be done once Shabbat ends?
The leniency applied only to Shabbat itself. After Shabbat, one must separate tithes as demai from the entire amount — including what was eaten — as the trust extended no further than the sacred day (Halachah 2).
Question 3
An unreliable person is seen separating first tithes from his produce, then claims he also separated second tithes. What is the ruling?
One who willingly gives away first tithes (to the Levite) has demonstrated real commitment, so we trust his claim about second tithes (which he retains). The reverse does not hold: separating what benefits you does not prove you separated what you must give away (Halachah 5).
Question 4
A wayfarer has lived in a new city for 30 days and still knows no one. From whom may he now purchase produce?
After 30 days, the stranger leniency expires. The person has had ample time to identify trustworthy sellers, so he is now held to the standard requirement of purchasing only from those with an established reputation for observance (Halachah 8).
Question 5
For which of the following items would a poor person's word be accepted that it came from leket, shichachah, or pe'ah?
The poor are trusted about produce in the natural, unprocessed form in which it is customarily given as field presents — such as grain, unhusked rice, or raw vegetables. Flour, bread, processed goods, and oil from leftover olives are not accepted because they require additional steps beyond normal field-gift giving (Halachot 12–14).