The things the Prophet (peace be upon him) said and did, he said and did in response to specific situations that arose in people's daily lives; none of them occurred in a vacuum. Hence, they were necessarily tied to practical situations of one sort or another. This is one of the most significant aspects of the distinction that must be made between the Quranic text, which for the most part contains universal principles, and the ‘'prophetic text,' which issued for the most part from concrete, changing circumstances.
When the hadith narratives portraying the life of the Prophet came to be viewed as themselves constituting the Sunnah, messages that had once been specific to defined situations came to be viewed as though they were intended for general application. However, most of the things the Prophet did and said were not only responses to specific, concrete situations, they were also, and no less importantly, reflections of his humanness. The Quran commanded the Prophet on numerous occasions to declare openly that he was only a human being. And in fact, he took care to emphasize this fact.
Consequently, the Prophet's humanness disqualifies many of his words and actions from being treated as the basis for binding legislation. He made this point explicitly clear in the well-known incident in which he expressed the view that the pollination of palm trees was not a useful practice, after which he reconsidered what he had said in light of his lack of knowledge about such matters, saying, "I am only human. So if I instruct you to do something relating to your religion, do as I say. But if I instruct you to do something based on my opinion, then remember that I am a mere human being." [Muslim] In another version of the same account, the Prophet was quoted as saying, "You all know best how to handle your worldly affairs." [Muslim] And in still another we read, "If I have supposed something to be true, do not take me to task for a mere supposition. But if I tell you something on God's authority, then act on it, for I would not lie about God." [Ibn Majah]
Herein lies the greatness, and earthiness, of this religion. Herein lies its fitness for all times and places. For here we find the Prophet himself drawing a decisive distinction between his abilities as Prophet and his abilities as mere human being, between personal opinion and religious instruction, between human attempts to discern truth and divine revelation, between worldly affairs and spiritual affairs, between what he says on his own behalf and what he says as God's representative. There exists, then, both revelation from God, which is binding as a religious duty, and earthly matters about which experts in the field concerned know best.
"Reviving The Balance: The Authority of the Qur'an and the Status of the Sunnah" - Taha Jabir Alalwani, pp. 140, 141