And he taught, saying unto them, is it not written,.... In Isa 56:7.My house shall be called of all nations, the house of prayer? For not only the Jews went up to the temple to pray, see Lu 18:10, but the Gentiles also, who became of the Jewish religion, and had a court built for that purpose; and so the whole temple, from hence, was called an house of prayer: and the meaning is, not only that it should be called so by the Gentiles, but that it should be so to them, and made use of by them as such.
Jarchi's note on the clause in Isa 56:7 is, "not for Israel only, but also for the proselytes."