A.T. Robertson Commentary Luke 2:27

"And he came in the Spirit into the temple: and when the parents brought in the child Jesus, that they might do concerning him after the custom of the law," — Luke 2:27 (ASV)

When the parents brought in the child Jesus (εν τω εισαγαγειν τους γονεις το παιδιον Ιησουν). A neat Greek and Hebrew idiom difficult to render into English, very common in the LXX;

In the bringing the Child Jesus as to the parents . The articular infinitive and two accusatives (one the object, the other accusative of general reference).

After the custom of the law (κατα το ειθισμενον του νομου). Here the perfect passive participle ειθισμενον, neuter singular from εθιζω (common Greek verb, to accustom) is used as a virtual substantive like το εθος in 1:8. Luke alone in the N.T. uses either word save εθος in Joh 19:40, though ειωθα from εθω, occurs also in Mt 27:15; Mr 10:1.