This week we read about Yitzchak going to Grar, due to famine in the Land of Israel. As he gets there, Hashem is revealed to him and says to him, not to go down to Mitzraym (Egypt). The obvious question on this is - why does Hashem need to tell him that? Who said he's on his way to Mitzraym?

When Avraham went down to Mitzraym due to famine, he went directly there - and now Yitzchak went to Grar - so why does Hashem need to tell him to stay in the Land of Grar, and not go to Mitzraym?!

What's this whole story about - what is Yitzchak doing in Grar??