Following the "bread and wine" incident of Genesis 14:18, Abraham asks for clarification of his status with God, because earlier, in Genesis 12, God had implied that Abraham's family would be great. After Abraham asks for clarification, God give the promise using an illustration involving stars. In order for Abraham to see stars, this event had to take place at night.
Notice Exodus 12:5-6:
Your [Passover] lamb shall be without blemish, a male of the first year; you shall take it out from the sheep, or from the goats: And you shall keep it up until the fourteenth day of the same month: and the whole assembly of the congregation of Israel shall kill it in the evening.
This is one of those places where the word "evening" is from the term in Hebrew ben ha arbayim. In modern English it means "twilight" or "dusk." The meaning of this word describes the time that the sun has gone down, but light continues to remain for a period of time. At this time of the year, the light would have lingered very close to about 45 minutes. After that, it would be dark.
Abraham is brought bread and wine by Melchizedek. The next thing we see in Genesis 15 is the mention of "stars"; it is dark. The Passover takes place in that period of dim light before it becomes dark. That is the time that we, in our observance, normally take Passover, just as the sun goes down. That is where the opening of Genesis 15 is time-wise. By the time you see stars, it is dark. We are beginning to see that time is moving in this episode.
When ben ha arbayim takes place, the Abib 13 has ended and Abib 14, Passover day, begins. This is undoubtedly when Melchizedek brought forth the bread and wine. Then came Abraham's vision, when it was dark and the stars were out. It is clearly into Abib 14, because it is dark.
John W. Ritenbaugh
The Wavesheaf and the Selfsame Day
Twilight is clearly past and now—with stars visible—it must be the dark part of Nisan 14. Both John 13:30 and I Corinthians 11:23 confirm the same general time in the events of Christ's final Passover. The daylight portion of the 14th is approaching.
John W. Ritenbaugh
Countdown to Pentecost 2001
Abraham was concerned that he had no children. In this section, God promised him that he would have countless children. Into this comes faith; Abraham believed Him. It is that simple. When it says that Abraham believed, we can understand from James 2 and elsewhere that his belief motivated him to submit—to obey God.
John W. Ritenbaugh
The Covenants, Grace, and Law (Part Twenty-Seven)
Genesis 14—15 contains time markers that help us line up these events with the Passover and Exodus from Egypt, as well as the Passover and crucifixion in the New Testament:
» “Then Melchizedek king of Salem brought out bread and wine; [H]e was the priest of God Most High” (Genesis 14:18). This corresponds with Jesus' Passover observance with bread and wine, which took place at the beginning of the 14th.
» “Then He brought him outside and said, 'Look now toward heaven, and count the stars if you are able to number them.' And He said to him, 'So shall your descendants be'” (Genesis 15:5). Abraham is outside and viewing the stars. The time has progressed to full dark on the 14th.
» The sacrificial activities described in Genesis 15:9-11 indicate the arrival of the daylight portion of Abib 14; it was light enough to make sacrifices. This method of making a covenant symbolizes that, if the terms were not met, the transgressor must be cut in half, just like the animals (see Jeremiah 34:18-20).
» “Now when the sun was going down, a deep sleep fell upon Abram; and behold, horror and great darkness fell upon him” (Genesis 15:12). The sun begins to go down as soon as noon has passed, so this verse could indicate any time in the afternoon or early evening.
» “And it came to pass, when the sun went down and it was dark, that behold, there appeared a smoking oven and a burning torch that passed between those pieces” (Genesis 15:17). The sun has set and Abib 15 has begun. The symbol of a burning lamp is linked with the salvation of God's people (Isaiah 62:1) and describes the eyes of God (Daniel 10:6). In addition, when God descended on Mount Sinai in fire, its “smoke ascended like the smoke of a furnace” (Exodus 19:18). Through these symbols, God is seen confirming His covenant to Abraham by passing through the middle of the sacrificed animals.
What happened during the daylight portion of the 14th in Abraham's day was a conversation about inheriting the land, then Abraham divided and arranged the animals at God's command in preparation for the covenant. Thus, the timing of Christ's crucifixion on the afternoon of Abib 14 points to something centuries before the Passover in Egypt—to the promises God made to the father of the faithful and to the preparations made for their covenant.
David C. Grabbe
Why Was Jesus Not Crucified as Passover Began? (Part Two)
Other Forerunner Commentary entries containing Genesis 15:5: