John 5:9
9. the same day was the sabbath—Beyond all doubt this was intentional, as in so many other healings, in order that when opposition arose on this account men might be compelled to listen to His claims and His teaching.
John 5:16
16. because he had done these things on the sabbath day—What to these hypocritical religionists was the doing of the most glorious and beneficent miracles, compared with the atrocity of doing them on the sabbath day! Having given them this handle, on purpose to raise the first public controversy with them, and thus open a fitting opportunity of laying His claims before them, He rises at once to the whole height of them, in a statement which for grandeur and terseness exceeds almost anything that ever afterwards fell from Him, at least to His enemies.
John 5:18
18. God was his Father—literally, "His own [or peculiar] Father," (as in Ro 8:32). The addition is their own, but a very proper one.
making himself equal with God—rightly gathering this to be His meaning, not from the mere words "My Father," but from His claim of right to act as His Father did in the like high sphere, and by the same law of ceaseless activity in that sphere. And as, instead of instantly disclaiming any such meaning—as He must have done if it was false—He positively sets His seal to it in the following verses, merely explaining how consistent such claim was with the prerogatives of His Father, it is beyond all doubt that we have here an assumption of peculiar personal Sonship, or participation in the Father's essential nature.