Is the one who asks considered sinful for the oath of the person who swore to pay but did not do so, by the asker's leaving him to pay?

The questioner incurs no sin for what was done, and fulfilling the oath of one who has sworn is desirable, not obligatory. It is applicable when there is no harm or corruption involved. There is no sin on theayer, and he must expiate for his oath if it is not fulfilled. The expiation is on the one who swore himself, because he is the one who broke the oath.