Martin Luther did not see the selling of indulgences as valid.
In line 42, Luther States that the buying of indulgences is not a substitute for works of mercy.
In 47, Luther states that there is no commandment that people buy indulgences to save their souls
And in like 49, Luther states that while indulgences may be useful and while it may be nice to have the Pope on your side, there is no real value in them.