1. The Promise to Sarah and the Timing of Yitzchak’s Birth
We see here that [UNCLEAR: the king, representing the kingdom of Shura] comes to inform Sarah that she will have a child. Not only does he tell her she will have a child, but he is also very specific in his language. He uses the phrase ka’et chaya—at this time next year. What does ka’et chaya mean? The word ka’et refers to a set time, as Rashi explains. It means that at this same season, in the coming year, something significant will happen.
Rashi clarifies that when it says ka’et chaya, it refers to the same time next year, and indeed, Yitzchak is born exactly then. This is what Rashi is highlighting here: when you look later in the verse and see Yitzchak’s birth, Rashi connects it back to this promise and its precise timing.
2. The Concept of “Srita” and Its Implications
Rashi brings up the idea of srita—a marking or incision—in relation to this promise. Hashem made a srita, a mark in time or on the calendar, indicating when this event would occur. However, Rashi notes that this marking was not made at the moment Hashem was present with Avraham; rather, it was a sign for when the event would take place in the future.
This marking was not about where Hashem was at that moment but about where and when Yitzchak’s birth would be fulfilled. Specifically, it relates to when Pesach would fall out in the following year according to their calendar system.
3. Calendar Calculations Before Yetziat Mitzrayim
The discussion turns to how months and years were calculated before yetziat Mitzrayim—the Exodus from Egypt. Rashi mentions that months were counted as either full (thirty days) or lacking (twenty-nine days), resulting in an average month length of 29.5 days. There were eleven short months during those years.
The question arises: how did they adjust their calendar back then? Did they have leap years as we do today? If so, adjustments would be necessary for holidays like Pesach to fall in their proper seasons. Perhaps they simply followed a regular twelve-month cycle without any leap years or special adjustments since there was no commandment yet for shmiras chodesh—sanctifying the new month—or for keeping Pesach at its appointed time.
4. The Meaning of “Tishrei” and Early Calendar Practices
The term Tishrei refers to working with a twelve-month cycle without any leap months or special observances like we have today with shmiras chodesh sheniya—a second Adar—or other adjustments. It seems likely that before these mitzvot were given, people simply followed a straightforward lunar year without intercalation.
This raises questions about how Chazal understood these early calendar systems across different places and times. If there were any adjustments made back then, they would have been only general ones rather than precise calculations as we do now.
5. The Timing of Hashem’s Promise According to Rashi
The main point is that Pesach would never fall out at exactly the same time each year unless there were some kind of adjustment or marking made by Hashem regarding when Yitzchak would be born. Therefore, when Hashem made this srita, it wasn’t done at that moment with Avraham but rather as a sign for when it would happen in the future.
I believe Rashi doesn’t specify exactly how this worked but implies that Hashem marked off a specific time on the calendar for this miracle to occur—not necessarily tied directly to their current date but based on future calculations.
6. Comparing Statements: The Malach Versus Hashem’s Words
The parsha presents two statements: one from the malach (angel) and one from Hashem Himself regarding Sarah’s future child. The malach says one thing while Hashem says another directly to Avraham. Rashi points out that these are not identical statements—the malach cannot say everything explicitly because he is only an agent delivering Hashem’s message.
This distinction is important because it shows how prophecy and divine communication work: sometimes through intermediaries like angels who paraphrase or adapt messages according to their role.
7. Understanding “Mo’ed” in This Context
The term mo’ed—appointed time—comes up repeatedly in these verses and commentaries. Rashi discusses what exactly is meant by “the appointed time.” Is it referring only to yesterday? To three days ago? Or perhaps even further back?
The context suggests that “mo’ed” here means not just yesterday but also includes several days prior—a broader window around which these promises are anchored.
8. Summary: The Fulfillment of Hashem’s Promise
Tying all these points together, we see that Rashi explains how Hashem’s promise about Yitzchak’s birth was tied both to specific times on the calendar and broader cycles of divine providence and human calculation. The use of terms like srita, mo’ed, and references to early calendar practices all highlight how carefully orchestrated these events were according to both natural cycles and supernatural intervention.
This careful attention to timing underscores not just the miracle itself but also our understanding of how mitzvot related to time developed over Jewish history—from simple lunar cycles before Sinai to our complex system today.