What is the ruling concerning the oath required of the creditors?

Primary text

In every case where an oath is required upon the creditors, it is required of all of them. If they all swear the oath, the claimant takes what they claimed. If they refuse to swear (nakul), judgment is rendered for the claimant based on what they claimed, unless the oath is returned to the claimant (radd al-yamin), in which case the claimant swears and is entitled to the claim. If only some of them swear while others refuse, the ones who swore take their portion, and the ruling for the refuser is as mentioned.