Yunus, the gemstone craftsman lived in the neighborhood of the Imam and once the ruler gave him an expensive jewel to work on. Per chance when he was working on it, it broke. He came to the Imam and explained the matter who assured him that it would be all right. Yunus was restless; at last a messenger came summoning him to the court. Imam Ali al-Naqi(a.s) said: Go, everything will be all right. When Yunus came to court, the king asked him if he has finished polishing the stone. Yunus said the work was incomplete. The king said: There is a dispute among my two sons, so cut it up into two for each of them. Yunus promised to do that and felt happy that what the Imam had assured, proved true.
Biharul Anwar, Vol. 9, Chap 3, Pg. 133