This passage occurs in the Narrative Lectionary Year 4. It also occurs in the RCL as part of Genesis 28:10-19a.
Summary: Even in Sunday School we pick up on the irony (or simply unfairness) that God picks Jacob. A careful reading reminds us that of another irony: Jacob doesn't really pick up on God's global aims. The whole vision and promise of God speaks to much grander things than Jacob has in mind. While we might be tempted to slam Jacob's narrowness or immaturity (especially his absurd response in vs. 20-21), I think he speaks to the faith situation of a lot of people: Some sense of God's providence to others in the past, but little sense of God's provision for that particular individual and scarely any sense that God intends to bless others through that individual.
סלם ("sullam"; "ladder"; 28:12) This word could also mean "stairway" or "ramp." The NET Bible notes: There appears to be an Akkadian cognate simmiltu which has a specialized meaning of "stairway, ramp"; TWOT notes: "...Jacob's ladder, raised from earth to heaven (Gen 28:12). Some would suggest the translation "stairway" and liken the structure to a ziggurat, which is possible. However, there are other words for stairway, and ladders were used at a very early time."
I am not sure how much is at stake with this translation. Perhaps some don't like the idea of ladder theology (we need to climb to God through our deeds), but stairway theology doesn't seem an improvement.
Side bar: It is fascinating to think of angels going up and down a ladder, even a very big one. I either think of monkey-like creatures leaping everywhere; or human like creatures having to move very carefully up and down the ladder.
םלאך ("malak"; "messenger" or "angel", 28:12) Up until this point in the story, angels have only interacted with members of Abraham's family. This vision of numerous angels reminds the reader that God is very busy at work, not just with Jacob (or even his family).
הנה ("hennah", "behold"; 28:12 (2x), 13, 15) The writer continues to invite us to envision the sequence of events.
ברך ("baruch", "bless"; 28:14) The form of this word is interesting here.
A grammar review: If you recall from Hebrew, verbs can come in a variety of forms, such as "qal" or "niphal." While the rules are not entirely regular, these various forms suggest something about how that verb is being employed. The "niphal" form means the verb is passive (I was hit, for example) or reflexive (I hit myself), with the passive meaning the more common.
If the verb is translated in the passive, then this passage reads, "All the families of the earth shall be blessed through you and your offspring."
If this verb is translated in the reflexive form, then this passage reads, "All the families of the earth shall bless themselves through you and your offspring."
It is probably most natural here to use the passive translation; however, elsewhere in Genesis (26:4 see) God clearly uses another form that is reflexive with the blessing language.
The question is not whether God will use Jacob's seed to bless all the earth; the question is to what extent will Jacob's seed have in sharing this blessing with the rest of the earth. That seems like a very rich and if not haunting question about the abundance of God's blessing and our role in sharing this blessing. Interestingly, Jacob's response suggests that the blessing of the world is not significant to him.
σπερματι ("spermati"; "seed" or "offspring"; Septuagint, 28:14), Paul will pick up on the fact that in both the Hebrew and Greek, the word for "seed" is singular. Paul takes this to mean "an offspring" instead of "offspring" which he claims is Christ. While I have no problem with Paul's intrepretation, especially the thought that through Christ the whole world is blessed, it is worth noting that "offspring" rarely ever appears in the plural in Hebrew.
דבר ("debar"; "speak"; 28:15) The Bible does not say God "promises" here; rather, whatever God says will happen is a promise because God is faithful and always fulfills his word.