to say unto them, &c. = to say to them that (Greek. hoti) This day, &c. Note the force of "that", and see note on Luk_19:9. Mar_14:30 (where hoti is used), and contrast Luk_22:34, and Mat_21:28 (where hoti is absent).
unto. Greek. pros.App-104.
this scripture. Not the next clause of Isa_61:2, which He did not read. That was then doubtful, and is now postponed.