Musnad Ahmad

It is narrated from Sayyiduna Ali (may Allah be pleased with him) that once I submitted in the presence of the Messenger (peace be upon him), "When you send me somewhere, should I go as a molded coin (i.e., strictly following instructions) or should I make decisions after observing the circumstances there, because the person present at the scene sees what the absent one does not see?" He replied: "Rather, keep this in mind that the person present at the scene sees what the absent one does not see (and make decisions after observing the circumstances)."