covenant: unconditional.
thy seed. Here, the collective noun ser'a is shown to be plural by the words "after thee" (compare verses: Genesis 17:8; Genesis 17:9), and by the plural pronoun "their generations" (verses: Genesis 17:7; Genesis 17:9). This is not the verse referred to in Galatians 1:3; Galatians 1:16, but Genesis 21:12. See note on Genesis 21:12, where "seed" must be in the singular because of the verb.
everlasting. Hence Israel so called. Isaiah 44:7 margin.