Luke 17:7

The phrase ὃς εἰσελθόντι is ungrammatical as it stands as it combines incompatible grammatical forms.

The unusual syntactics led some scholars to say that to make sense of the clause grammatically, you need to mentally insert or supply the verb ἐστί before the relative clause introduced by ὃς (cf. Meyers NT).

If we do not wish to add words, ὃς must be connected with ἐρεῖ; syntactically, as it functions as the subject of that verb.

Greek word order is flexible, but case and syntax are not. In this clause:

• ὃς is nominative: only a subject (or predicate nominative, which this is not).

• There is no other nominative noun or pronoun to serve as subject of ἐρεῖ.

• Therefore, ὃς must be the subject of ἐρεῖ.