Notes on the Bible, by Albert Barnes, , at sacred-texts.com
There appears to have been an interval of some months between the preceding events and this renewal of the promise to Moses. The oppression in the meantime was not merely driving the people to desperation, but preparing them by severe labor, varied by hasty wanderings in search of stubble, for the exertions and privations of the wilderness. Hence, the formal and solemn character of the announcements in the whole chapter.
I am the Lord ... - The meaning seems to be this: "I am Jehovah (Yahweh), and I appeared to Abraham, Isaac, and Jacob as El Shaddai, but as to my name Jehovah, I was not made known to them." In other words, the full import of that name was not disclosed to them. See Exo 3:14.
God Almighty - Rather, "El Shaddai," (שׁדי אל 'êl shadday), it is better to keep this as a proper name.
With a stretched out arm - The figure is common and quite intelligible; it may have struck Moses and the people the more forcibly since they were familiar with the hieroglyphic which represents might by two outstretched arms.
They hearkened not - The contrast between the reception of this communication and that recorded in Exo 4:31 is accounted for by the change of circumstances. On the former occasion the people were comparatively at ease, accustomed to their lot, sufficiently afflicted to long for deliverance, and sufficiently free in spirit to hope for it.
For anguish - See the margin; out of breath, as it were, after their cruel disappointment, they were quite absorbed by their misery, unable and unwilling to attend to any fresh communication.
Go out of his land - Moses is now bidden to demand not a permission for a three days' journey (Exo 3:18 note), which might be within the boundaries of Egypt, but for departure from the land.
Uncircumcised lips - An uncircumcised ear is one that does not hear clearly; an uncircumcised heart one slow to receive and understand warnings; uncircumcised lips, such as cannot speak fluently. The recurrence of the hesitation of Moses is natural; great as was the former trial this was far more severe; yet his words always imply fear of failure, not of personal danger (see Exo 3:11).
Unto Moses and unto Aaron - The final and formal charge to the two brothers is given, as might be expected, before the plagues are denounced. With this verse begins a new section of the history.
These be the heads - We have in the following verses, not a complete genealogy, but a summary account of the family of the two brothers. Moses records for the satisfaction of Hebrew readers, to whom genealogical questions were always interesting, the descent and position of the designated leaders of the nation. See Exo 6:26-27.
Amram - This can scarcely be the same person who is mentioned in Exo 6:18; but his descendant and representative in the generation immediately preceding that of Moses. The intervening links are omitted, as is the rule where they are not needed for some special purpose, and do not bear upon the history.
Jochebed - The name means "the glory of Jehovah (Yahweh)," one clear instance of the use of the sacred name before the Exodus.
Father's sister - This was within the prohibited degrees after the law was given Lev 18:12 but not previously.
This emphatic repetition shows the reason for inserting the genealogy. The names of Moses and Aaron are given twice and in a different order; used in Exo 6:26 probably to mark Aaron as the older in the genealogy, and used in Exo 6:27 to denote the leadership of Moses.
This and the following verses belong to the next chapter. They mark distinctly the beginning of a subdivision of the narrative.
See Exo 6:12.