Albert Barnes on Luke 17:14

Go show yourselves, &c. Mt 8:4. By this command he gave them an implied assurance that they would be healed; for the design for which they were to go was to exhibit the evidence that they were restored, and to obtain permission from the priest to mingle again in society. It may also be observed that this required no small measure of faith on their part, for he did not first heal them, and then tell them to go; he told them to go without expressly assuring them that they would be healed, and without, as yet, any evidence to show to the priest. So sinners, defiled with the leprosy of sin, should put faith in the Lord Jesus and obey his commands, with the fullest confidence that he is able to heal them, and that he will do it if they follow his directions; and that in due time they shall have the fullest evidence that their peace is made with God, and that their souls shall by him be declared free from the defilement of sin.

Were cleansed. Were cured, or made whole.

(i) "Go show yourselves" Lev 13:2, 14:3, Mt 8.4, Lk 5:14 (k) "as they went" 2Kgs 5:14, Isa 65:24