Pesachim, Chapter 4, Mishnah 8. This mishnah deals with a series of questionable practices followed by the people of Jericho - long before a casino was built there. Some of these practices drew protest from the Sages, and some did not. The mishnah appears here because the first of these practices relates to doing work on erev Pesach.
"Shishah devarim asu anshei Yericho, al sheloshah michu b'yadam v'al sheloshah lo michu b'yadam":
The people of Jericho followed six practices: in three of them the Sages protested, and in three they did not.
The three in which they did not protest:
The first - the matter relating to doing work on erev Pesach. They did not protest, because they were concerned that if the work were not done immediately, the fruit would be ruined and the crop lost.
"V'chorchin es Shema" - as the Gemara explains, they would omit the words "Baruch shem kevod malchuso l'olam va'ed," and move directly from the first verse of Shema to "V'ahavta" - not in the order that the Sages established for reciting Shema.
"V'kotzrin v'godshin lifnei ha'omer" - they would harvest the grain and pile it into stacks even before the omer was cut and brought in the Beis HaMikdash. Now, the prohibition of harvesting before the omer applies specifically to grain that is fit to be used for the omer offering; and grain from irrigated fields, which require watering, is not brought as an offering. The people of Jericho harvested grain from irrigated fields, so the harvesting itself was permitted to them. But the stacking - piling the grain up - was not permitted until after the omer, and they did it anyway.
Even though these practices were improper, the Sages did not protest against these three.
"V'eilu shemichu b'yadam":
"Matirin gamziyos shel hekdesh" - the people of Jericho permitted benefiting from the gamziyos, the branches and growths that emerge from trees that had been consecrated. Their fathers had consecrated their trees because powerful men would seize their trees and parts of them. The people of Jericho held that only the main body of the tree was consecrated and not the rest, but this is not so: whatever grows from it is also hekdesh.
"V'ochlin mitachas hanesharim b'Shabbos" - they would eat on Shabbos fruit that had fallen beneath the trees. It is uncertain whether the fruit fell before Shabbos or on Shabbos itself; and if it fell on Shabbos, it is muktzeh, since at the onset of Shabbos it was still attached and could not be picked. This is a case of doubtful muktzeh, which is not permitted to be eaten, and nevertheless they treated it as permitted.
"V'nosnin pe'ah v'yarak" - they would give pe'ah to the poor and declare part of their vegetable field, of leafy vegetables, to be pe'ah - and consequently no Terumah or maasros would be taken from it. But halachically, leafy vegetables are not eligible for pe'ah, since one of the conditions for the obligation of pe'ah is that the crop be something that is brought in for storage, that is, something that can be stored, and leafy vegetables cannot be stored, certainly not without refrigeration. Since they are not subject to pe'ah, declaring them pe'ah is likewise ineffective, and the produce remains obligated in maaser.
In these three practices the Sages did protest.
In summary: In this mishnah we learned about six practices of the people of Jericho. In three the Sages did not protest: the matter relating to doing work on erev Pesach (out of concern for the loss of the fruit), "wrapping" the Shema by omitting "Baruch shem kevod malchuso," and harvesting and stacking before the omer. And in three they did protest: permitting the gamziyos of hekdesh, eating fruit that fell on Shabbos despite the doubt of muktzeh, and giving pe'ah from vegetables that are not subject to it.