17:1-10 It is no abatement of their guilt by whom an offence comes, nor will it lessen their punishment that offences will come. Faith in God's pardoning mercy, will enable us to get over the greatest difficulties in the way of forgiving our brethren. As with God nothing is impossible, so all things are possible to him that can believe. Our Lord showed his disciples their need of deep humility. The Lord has such a property in every creature, as no man can have in another; he cannot be in debt to them for their services, nor do they deserve any return from him.
7-10. say unto him by and by—The "by and by" (or rather "directly") should be joined not to the saying but the going: "Go directly." The connection here is: "But when your faith has been so increased as both to avoid and forgive offenses, and do things impossible to all but faith, be not puffed up as though you had laid the Lord under any obligations to you."