Another example of customs unique to specific communities was that the people of Jericho, “the city of date palms” (see 34:3), permitted grafting of date palms throughout the day of erev Pesah. Rav Aha the son of Rava explains this to mean placing a branch of a male palm tree on the female.
Date palms are dioecious, that is each tree is specifically male or female. A male tree does not produce dates, but is necessary for its pollen in order for the female tree to give fruit. In nature or in orchards where the palm trees are planted very close together, the wind is enough to fertilize the female trees. When growing date palms commercially to produce dates, however, hand pollination is usually necessary to insure a good fruit harvest. Male flowers should be collected within a few hours after the sheath splits open to prevent pollen loss. The pollen should be stored in a cool place until the female florets on the female tree are ready for pollination. Three or four strands of the male flower should be placed with the female strand from one to three days after the female sheath splits open.
Once the female tree is ready to be fertilized, time is of the essence. Therefore we can well understand the concern in Jericho that hand pollination should be permitted throughout the day on erev Pesah.
Following the Mishnaic teaching about the six customs of the people of Jericho, the Gemara tells of six actions of King Hizkiyahu, three of which received the approval of the Sages, three of which did not. One of King Hizkiyahu’s activities was suppressing the sefer refu’ot, the Book of Cures, from popular use. What was this sefer refu’ot?
In Maimonides’ commentary to the Mishna, he argues that if this were simply a book of medicine from which the sick could be healed it should have been valued and used, and the Sages would never have agreed to allow it to be hidden away. He offers two possible explanations:
1. It was a book that listed a variety of forbidden activities that could have an effect on a given illness, which was written as a theoretical treatise, examining nature. When people began to use it in practice, King Hizkiyahu removed it.
2. It was a book that described how to make poison and its antidote. While the intent was to allow a doctor to heal someone who had become poisoned, when people used it to learn how to injure others, it was hidden away.