The material establishes that Passover must be observed at twilight on the fourteenth day of the first month, identifying this timing as the evening that begins Nisan 14 rather than the following daylight hours or the fifteenth. Multiple Old Testament instructions specify the fourteenth for the Passover, and the phrase rendered "at twilight" or "even" translates the Hebrew expression that first appears in Genesis 1:5. There God defines the evening as the night portion that opens each day, followed by the morning, so that the same term denotes the period beginning at sunset. This definition shows that twilight marks the start of Nisan 14 before any daylight arrives. The requirement that the Passover and the Feast of Unleavened Bread occupy separate days, with the latter beginning on the fifteenth, further confirms that the Passover sacrifice occurs at the evening opening the fourteenth. The command to keep the lamb until the fourteenth day and then kill it at twilight reinforces that the appointed moment falls at the evening that commences the fourteenth, not later. These clear statements determine the correct observance and exclude any practice that would shift the Passover into the fifteenth.

The Passover lamb was killed in the evening of the 14th of Abib, the literal Hebrew indicating between the two evenings. This phrase denotes the twilight period after the sun goes down, when the new day has commenced, but before darkness when the stars appear. The lamb was therefore slain at the very beginning of the 14th, immediately after sunset. Jesus observed this same appointed time when He instituted the New Testament Lord's Supper on the eve of His crucifixion, taking the bread and the cup as they were eating the Passover meal. By following His example, the ordinance is to be kept once each year at this exact scriptural hour after sundown on the 14th, the anniversary of His death. Observing it at any other time would constitute partaking unworthily, just as the Israelites would have done had they killed the lamb outside the divinely specified twilight window. This timing preserves the memorial character of the event and maintains continuity with the original ordinance commanded to continue forever.

Twilight, designated in Scripture as ben ha arbayim, follows ba erev and marks the gradual transition from remaining light into darkness. This interval, lasting roughly one hour in spring and lengthening slightly by midsummer before shortening again, begins with substantial light and ends in deepening dusk. It constitutes the precise window during which the Passover lambs were slain at the start of the fourteenth day, immediately after sunset had concluded the thirteenth. The sequence is anchored in the creation account, where God separates light from darkness and names them distinct portions of the day, and is reinforced by the plague narratives showing boqer arriving only after the full course of lailah. These definitions establish that ben ha arbayim cannot overlap with midnight or the dark hours that follow. The timing therefore fixes the entire Passover observance, including killing, roasting, eating, and disposal of remains, within the fourteenth from sunset onward, while the departure from Egypt occurs on the fifteenth. This scriptural precision counters attempts to equate morning with night or to compress the events into fewer hours, demonstrating that doctrine must derive solely from the Bible's own consistent usage of terms rather than external traditions or modern English conventions.