Genesis 21:4

Summary

The verse reports that Abraham circumcised his son Isaac when Isaac was eight days old, and it notes that this act conformed to a prior command given by God. The sentence links the action directly to divine instruction through a comparative clause.

Key words

• va-yamol ("and he circumcised", H4135A) — qal verb in the narrative vav pattern, marking this as the next sequential event in the story after Isaac's birth.
• ben-shemonat yamim ("son of eight of days", H1121L + H8083 + H3117G) — a construct chain literally "a son of eight of days," the standard Hebrew idiom for stating age in days.
• ka'asher ("as", H0834D) — relative particle preceded by the preposition ka ("just"), introducing a clause of correspondence between Abraham's action and an earlier command.
• tzivvah ("he had commanded", H6680) — piel perfect verb; the perfect aspect marks this command as prior to and completed before the circumcision described in the main clause.
• Elohim ("God", H0430G) — grammatically plural noun functioning as the subject of tzivvah, the one who issued the command.

What the text says

The main clause is built on the pattern va-yamol Avraham et-Yitzchak beno — "and Abraham circumcised Isaac his son" — using the narrative vav construction typical of Hebrew storytelling, which presents this as the next event following the preceding narrative. The object marker et (H0853) before "Isaac" signals that Isaac is the direct object of the circumcising, and the phrase beno ("his son", H1121A + suffix H9023) identifies the relationship explicitly even though it was already established in prior verses.

The age notation ben-shemonat yamim uses a double construct chain: "son" is in construct with "eight," and "eight" is in construct with "days," producing the idiom "a son of eight of days" to mean "eight days old." This is a formulaic way Biblical Hebrew states age, distinct from stating a date or a duration with other grammatical means.

The final clause, introduced by ka'asher ("as," combining ka "just" and asher "that/who"), draws a direct parallel between Abraham's action and the divine instruction. The verb tzivvah is in the piel perfect, an intensive verbal pattern often used for authoritative commands, and its perfect aspect places the commanding action as already completed relative to the circumcision — the command came first, the action follows in accord with it. The subject Elohim, though morphologically plural, functions here as a singular subject governing the singular verb tzivvah.

Differences between versions

The Hebrew places the note about Isaac's age ("son of eight days") immediately after his name, inside the main clause. The LXX renders this with τῇ ὀγδόῃ ἡμέρᾳ ("on the eighth day"), a dative time expression rather than the Hebrew's construct "son of X days" idiom. The Vulgate similarly uses octavo die ("on the eighth day"), matching the LXX's temporal phrasing rather than reproducing the Hebrew construct chain. The BSB restructures the sentence order, placing the age clause first ("When his son Isaac was eight days old"), which differs from the Hebrew word order where the circumcision verb opens the sentence.