An excerpt from Chapter IV, "The Preservers of Hadith and Scholars of Law Among the Companions" from his book "The History of the Codification of Islamic Law"

Abu Huraira (God be pleased with him) was one of those eminent Companions who were distinguished in the line of preserving and reporting the Holy Prophet's Traditions, and this is borne out by the large number of Traditions reported by him and included in the books of Hadith. But it is a fact well-known to the students of the history of Companions, that whenever someone was confronted with any religious or legal problem, he would not approach Companions like Abu Huraira but those who were considered Fuqaha (i.e., men of grasp and understanding). It was this latter class whose verdict (fatwa) was relied upon and whatever interpretation they gave to the Sayings and Actions of the Holy Prophet (peace be with him) was accepted. 

To make the distinction between the two categories of Companions practically clear, I may invite your attention to a famous Hadith. 

One day, the Holy Prophet went to a garden, in search of solitude, without telling anyone. Compelled by their intense love, the Companions became anxious after some time and started out in different directions to find him. Abu Huraira succeeded in his attempt. He saw the Holy Prophet sitting on a well, in quiet spiritual repose and absorbed in communion with God. Finding Abu Huraira by his side, the Holy Prophet (peace be with him) turned towards him and said, "Whosoever recited 'there is none worthy of worship but Allah ' shall enter paradise." 

Abu Huraira heard that heartening message and was overjoyed, feeling that the problem of salvation had become so simplified. He sought the permission to make it known to others. The Holy Prophet who was presumably in a special spiritual state at that time, replied, " yes." 

Forthwith, Abu Huraira started for the town. But he had not gone far when he met Umar, who himself was engaged in a search of the Holy Prophet. Abu Huraira told him about the Holy Prophet and also mentioned the Holy Prophet's Saying just referred [to]. Umar asked him about his destination. Abu Huraira informed him that he was going to the town to broadcast the Holy Prophet's Saying among the people. Umar said : "No! don't proclaim it." Abu Huraira insisted that he would. Umar insisted that he should not. At last both came to the Holy Prophet. Umar implored, "O Apostle of God! If people will be informed of this Hadith at the present stage of Islamic culture, they will stick to its literal connotation that the recitation of the Kalima (article of faith) is enough for salvation and will leave Islamic actions." The Holy Prophet expressed his approval of Umar's point of view.

Now, this clearly shows that Islamic scholarship does not consist merely in the ability to read Arabic, but in the capacity to reach the inner depths of the teaching contained in the Qur'an and the Hadith. Take, for instance, the Hadith in question. To recite the Kalima with the tongue is meaningless unless it expresses the corresponding conviction. And conviction means nothing less than actually submitting oneself to God's commands and the Holy Prophet's leadership. It comprehends within itself the whole sweep of Islamic life. In those early days of Islam, the apprehension was justified that people might take the Holy Prophet's Saying literally. Hence the Faqih-ul-Millat, the Wise man of the Community, Umar the Great, about whom the Holy Prophet (peace be with him) declared: "Verily, God manifested truth on the tongue of Umar," he did not consider it proper to acquaint the people with that Hadith at that time and the Holy Prophet approved his judgment. 

In short, it was the principle followed by the Companions, that whenever they had to find out about some religious or legal problem, they would invariably approach those Companions for guidance who were considered to possess not only the knowledge of the words of the Qur'an and the Hadith but also superior insight and understanding and were thus entitled to guide others. 

This principle was followed during the whole period of Righteous Caliphate. For the interpretation and execution of Islamic Law, there was an Advisory Council which was composed of such Companions who were considered to be most capable in matters of religion and law. The Amir-ul-Mumineen was always the President of the Council and whenever there was a disagreement on some legal point between the members, it was his prerogative to give the final verdict.