According to the teaching of Rabbi Yohanan on today’s daf , it is forbidden to engage in marital relations during the day. Both Rabbi Yohanan and Resh Lakish quote biblical passages in support of this ruling, Rabbi Yohanan from the book of Iyov (3:3) and Resh Lakish from the book of Mishlei (19:15).
In discussing each of these passages, the Gemara suggests different interpretations that each of these Sages would give to the proof-text offered by the other, and Rabbi Yohanan is said to use Resh Lakish’s passage to teach an idea that is found in the book of Ben Sira.
Sefer Ben-Sira is one of the earliest books composed after the closing of the Biblical canon. It was authored by Shimon ben Yehoshua ben Sira, a native of Jerusalem, who was a younger contemporary of Shimon haTzaddik, prior to the Hasmonean era. The book of Ben-Sira was held in great esteem, and after its translation into Greek by the author’s grandson (in the year 132 BCE in Alexandria) it became widely known even among those who were not familiar with the Hebrew language. Sefer Ben-Sira is included as a canonical work in the Septuagint (and therefore is considered as such in many other translations of the Bible), and although the Sages chose to view it as one of the sefarim hitzoni’im – books outside of the canon – they quote it in a respectful manner throughout the Talmud, sometimes even referring to it as ketuvim. Still, because of confusion between this work and another one that was known as Alfa-Beta d’Ben-Sira, which was a popular – and problematic – work, we find statements in the Gemara forbidding the study of Sefer Ben-Sira.
For generations Sefer Ben-Sira was known only from its translations, but recently parts of it have been found in the original Hebrew (in Masada and elsewhere). Since it was not part of the official Biblical canon it appears that the copyists felt more freedom when working with it and we find several different versions of the same text. When it appears in the Talmud it seems likely that it is being quoted by heart by the Sages, rather than from a written text.
Although Rabbi Yohanan’s teaching forbidding sex during the day is presented by our Gemara without argument, on tomorrow’s daf Rava permits such relations under certain circumstances (e.g., if the room is darkened). In fact, the Gemara in Massekhet Ketubot (65a) relates a story about Rava where it is clear that he and his wife engaged in marital relations during the day.