This is to emphasize that an oath should not stop an important good work, or prevent one from doing a significant duty or job:
``Allah will not call you to account for slip in your oaths.'' This verse alludes to two sorts of oaths:
1) One which is merely an idle talk without worth or basis. God calls this not to account, and it has no expiation, but should be stopped anyhow. When it has been a thoughtless oath with no intention behind it, it may be expiated and cleared by an act of charity.
2) The second kind of oath is that which is taken intentionally and earned by hearts, as Qurän has pointed in this verse. - Such an oath is a sin, and calls for expiation in order to get rid of its inauspicious consequences.