Arcana Coelestia #2631
2631. Verse 4 And Abraham circumcised his son Isaac, a son eight days old, as God had commanded him.
'Abraham circumcised his son Isaac' means purification of the rational. 'A son eight days old' means a beginning and continuation. 'As God had commended' means according to Divine order.
Arcana Coelestia #2630
2630. 'Isaac' means the Divine Rational. This is clear from what has been stated already about Abraham, Isaac, and Jacob in 1893, 2066, 2083, to the effect that 'Abraham' represents the Lord's Supreme Divine, 'Isaac' the Divine Rational, and 'Jacob' His Divine Natural, as will also be clear from what comes later on where Isaac is the subject.