Mark 9:19

Faithless. That is, “without faith,” or “unbelieving.” Compare God’s appraisal of Israel during the days of Moses (see Num. 14:27; Heb. 3:17-19). It does not seem likely that Jesus had the father of the demon-possessed boy in mind as He spoke these words, for the father’s faith was not the only obstacle in the way of the healing of his son. Because the disciples themselves were primarily at fault (see on Mark 9:29), it would almost seem that the Saviour had them in mind particularly. But He did not desire to single them out for censure in public, and so did not make them the direct object of His remarks. However, if the disciples were “unbelieving,” how much more the crowd.

How long? These words imply that Jesus here speaks as a divine being, one who has temporarily assumed human form.

Suffer you. Literally, “endure you,” or “sustain you.” Moses repeatedly had the same experience with Israel in the wilderness (see Num. 20:10).