chaya sara

כי אל ארצי ואל מולדתי תלך ולקחת אשה לבני ליצחק
To my land & my birthplace you shall go & take a wife for my son for yitzchak. 
Avraham tells Eliezer to go back to his hometown and find a wife for Yitzchak. 
Why was Avraham so insistent that Eliezer take a wife for יצחק from his family? Didn't 'ה just tell him in לך לך to leave his family? 
The Posuk says Avraham says לא תקח אשה לבני מבנות הכנעני אשר אנכי יושב בקרבו "don't take a woman for my son from the daughters of the Canani that I'm living in their midst"
The Chasam Sofer asks, if he wouldn't be living among them, then he could take from them? why is living among them a reason why יצחק couldn't marry them? 
Then a few Pesukim later he says even if she won't come with you -פן תשיב את בני שמה " no matter what, don't bring my son there"
Which means that even if he would have to go find a less appropriate shidduch, that would be ok as long as יצחק doesn't go back there. R' Moshe asks, why was he so adamant that יצחק not go back there under any circumstances?
He answers that Avraham is teaching us how important our surroundings are & how we have to try to be close to Talmiday Chachamim. We see that even people like יצחק & רבקה who were on such a high level,could be affected by their surroundings Avraham was worried that if they would live out there with no positive influences around, they would come to fall from their great level. 
That's why he said under no circumstance could they live there but had to stay close to him. 
Similarly says the Chasam Sofer, the reason that he couldn't take a Canaani girl was because he lived amongst them. If the girl came into his house he could have a positive influenced on her,but once she was around her family again, all that she learned by Avrham would be lost. 
That's why he said take from my father's house & bring her here so that she'll be surrounded by positive influences instead of the negative influence of her family.  
That could be what 'ה was telling him too when he said to leave his father's house - to go away from the negative influence of his hometown.  
He felt that as long as he brought the girl to him & took her away from the negative influences into a home of positive influences, he was really doing what 'ה had told him to do ; to take people & bring them closer to 'ה!