2 Kings 5:13

And his servant came near, and spake unto him, and said, my
father
Or my lord, as the Targum; this being not a familiar and affectionate expression, but a term of honour, reverence, and submission:

if the prophet had bid thee do some great thing, wouldest thou not have
done it?
something that was hard and difficult to done, or painful to bear, to go through some severe operation, or disagreeable course of physic:

how much rather then when he saith to thee, wash, and be clean?
which is so easy to be done; though Abarbinel observes it may be interpreted, the prophet has bid thee do a great thing, and which is wonderful; for though he has said, wash and be clean, consider it a great thing, and which is a wonderful mystery, and therefore do not despise his cure.