so the king said to me, “Why is your face sad, though you are not ill? This could only be sadness of the heart.” I was overwhelmed with fear
When Nehemiah had prayed for the relief of his countrymen, and perhaps in David's words (Psa 51:18, Build thou the walls of Jerusalem), he did not sit still and say, "Let God now do his own work, for I have no more to do," but set himself to forecast what he could do towards it. our prayers must be seconded with our serious endeavours, else we mock God.
Commenting on Nehemiah 2:1-8
Wherefore the king said unto me, why is thy countenance sad, seeing thou art not sick?.... He had no disorder upon him to change his countenance and make him sorrowful, and therefore asks what should be the reason of it: this is nothing else but sorrow of heart; this is not owing to any bodily disease or pain, but some inward trouble of mind; or...
the king said unto me, Why is thy countenance sad?--It was deemed highly unbecoming to appear in the royal presence with any weeds or signs of sorrow (Est 4:2); and hence it was no wonder that the king was struck with the dejected air of his cupbearer, while that attendant, on his part, felt his agitation increased by his deep anxiety about the issue of the conversation so abruptly begun.