Fafahhamnaha sulaymana wakullan atayna hukman waAAilman wasakhkharna maAAa dawooda aljibala yusabbihna wattayra (surah Anbiya: 79)

Tafseer Tafheem-ul-Quran by Syed Abu-al-A'la Maududi

(21:79) At that time We guided Solomon to the right decision, though We had bestowed wisdom and knowledge upon both of them. *70

Fafahhamnaahaa sulaimaan; wa kullan aatainaa hukmanw wa`ilmanw wa sakh kharnaa ma`a Daawoodal jibaala yusabbihna wattayr; wa kunnaa faa`ileen

*70) There is no mention of this event in the Bible nor in the Jewish literature. According to the Muslim commentators, it happened like this: The goats of one person entered into the field of another person at night. The latter brought his complaint to Prophet David who decided that the strayed goats should be given to the owner of the field. Prophet Solomon, however, differed with this and opined that the goats should remain with the owner of the field up to the time that the former tilled and prepared the field as before. In regard to this Allah says, "We led Solomon to the right decision". As regards the legal aspect of the matter we cannot say with certainty what is the Islamic law in such a case nor is there any Tradition of the Holy Prophet to explain or support it. That is why the jurists have differed about it.
It should, however, be noted that in this context, the incident has been cited to show that the Prophets were after all human beings in spite of their Godgiven powers and abilities. In this case, Prophet David committed an error of judgment because he was not guided by AIIah as was Prophet Solomon, though both of them were Prophets. In the succeeding passage the wonderful powers of both have been mentioned to show that they were God-given and did not snake anyone a god.
Incidentally, we learn froth this verse that if two judges give different decisions about one and the same case, both of them will be regarded as righteous, though the decision of only one of them will be correct, provided that both are duly qualified for sitting in judgement on the case. The Holy Prophet has stated the same principle more elaborately. In a Tradition of Bukhari, he is reported by 'Amar bin 'As to have said, "If a judge does his very best to arrive at the right decision, he will get a double reward in case of a right judgment and a single reward if his judgment is wrong." According to another Tradition, cited by Abu Da'ud and Ibn Majah, on the authority of Buraidah, he is reported to have said, "Judges are of three kinds and only one of them will go to Paradise: the one who recognizes the Truth and decides according to it. On the other hand, the one who recognizes the Truth but gives his decision against it, will go to Hell, and he too, who sits in judgment on a case without the necessary knowledge (and competence). "