Witnesses in Jewish Law

Where is there a source in Jewish Law that states that someone who eats a meal in the marketplace becomes disqualified from serving as a witness?

The Mishnah and Babylonian Talmud in Tractate Kiddushin page 40b discuss this topic. The text from the Soncino translation (Epstein, Rabbi Dr. I. The Babylonian Talmud. London: Soncino Press, 1935-1948) reads as follows:

“MISHNAH. HE WHO IS VERSED IN BIBLE, MISHNAH, AND SECULAR PURSUITS10 WILL NOT EASILY11 SIN, FOR IT IS SAID, AND A THREEFOLD CORD IS NOT QUICKLY BROKEN.12 BUT HE WHO LACKS BIBLE, MISHNAH AND SECULAR PURSUITS DOES NOT BELONG TO CIVILISATION.BUT HE WHO LACKS BIBLE, MISHNAH [etc.]. R. Johanan said: And he is unfit to testify.”

Talmud: “Our Rabbis taught: He who eats in the market-place is like a dog; and some say that he is unfit to testify. R. Idi b. Abin said: The halachah agrees with the latter.”

Rashi on this topic offers a reason for this law, namely that such a person acts in an undignified manner and as such lacks self-respect. Someone who lacks self-respect will not feel embarrassed about testifying falsely. The Tosafist commentators question Rashi’s reason based on other sources that imply that it is undignified only for a Torah scholar to eat in the marketplace, but for others not, and offer three other possible reasons. The first reason explains that the person snatches/steals food and eats. The second reason explains that the person goes around from vendor to vendor, tasting a little bit of each food, as though he were to purchase it but then doesn't. The third reason quotes the Tosafist commentator Rabbeinu Tam as saying that the concept refers to someone who eats a complete meal of bread (seudah) while in the market, which is considered more disgraceful. Both Rashi's and the Tosafists' explanations offer reasons that eating in the marketplace might have negative connotations for serving as a witness. 

Dots in Rashi

Question:
I am interested in the dots used to separate the various sections of Rashi's commentary to Torah and Talmud. Are these dots found in early printed editions of Rashi or are they a later innovation?
Answer:
There are two considerations in separators, one is the marker of the end of the lemma, the other is the marker of the end of the comment. Usage has not been consistent, but development may be seen. There is enough variation to suggest that a wider range may even be found in mss., but that would be another inquiry. In Rashi on the Torah, I looked at ed. Rome 1489/92 and Soncino 1487. Ed. Rome used no punctuation only spaces to separate lemmata and commentary, as well as divisions within commentary, nothing even at the end of a chapter. Soncino, OTOH, separated lemma with one dot and marked end of comment with two vertical ones or one. In Talmud, progress went from nothing after lemma to marking it. Soncino 1487 used one dot to mark end of comment. An unkown Spanish edition, ca. 1482, used two vertical dits or two horizontal ones (sometimes just one). Other printed edns. (random sampling of 16th & 17th cent., items) separated comments with two vertical dots, but did not mark end of lemmata, except for Cracow 1603 Pesahim which sometimes separated lemma with single dot. By the 18th cent., many editions separated comments with two dots and ended lemmata with single dot, e.g., Frankfurt a/M 1720, Berlin 1734, Sulsbach, 1766, and so into the 19th cent. (except that Slavuta 1817 did not mark end of lemmata). It should be noted that some editions also used spacing to separate comments. Also noteworthy is that single dots can come at top of line, bottom, and center.
(Answer provided by Dr. Jay Rovner, JTS Library's Manuscript Bibliographer.)