William Burkitt on Luke 17:15

Observe here, 1. All were healed, but only one was thankful; the cure is wrought upon the bodies of all, thankfulness if sound but in the heart of one: the will makes the difference in men, but he makes the difference in wills, who at first made the will. All these lepers were cured, all saw themselves cured; their sense was alike, their hearts were not alike.

Observe, 2. The person that made this return of thankfulness to Christ, He was a Samaritan: that is, none of the Jewish nation, but one that was a stranger to the commonwealth of Israel: neither place nor parentage can block up the way, or stop the current, of God's free mercy, which reaches the unworthy and the ill-deserving.

Observe, 3. How singly he returns his thanks; he gets away from his fellows to make his acknowledgment: there are cases wherein singularity is not only lawful, but laudable; instead of sujecting ourselves to others; examples, it is sometimes our duty to resolve to set an example to others; for it is much better to go the right way alone, than to err with company.

Observe, 4. How speedily he returns his thanks: no sooner does he see his cure, but he hastes to acknowledge it: a noble pattern of thankfulness. What speed of retribution is here! Late payments of our thankfulness savor of ingratitude: it were happy for us christians, did we learn our duty of this Samaritan.