What really was behind Lavan's introductory statement "If I have now found favor in your eyes"?
Seforno: What Lavan really meant to say was, 'If you love me (which, bearing in mind our family relationship you really should), then it is not right that you should leave me'. 1
What he had in mind of course, was that the Berachah that Yakov brought with him, should continue unabated.
What did Lavan mean when he said "Nichashti ... "?
Ramban #1, Targum Onkelos and Seforno #1: He had arrived at that conclusion by trial, based on the fact that, since Yakov's arrival, his business-ventures had flourished way above normal, a clear indication of Yakov's righteousness. 1
Malbim: All my Brachah is due to you. If you will leave, I will return to be poor. I did not give my daughters on such condition. This is like a buyer who throws the coins [paid for the sale item] to the sea. He nullifies the sale! 5
Ha'Emek Davar: Do not claim much for your work. The Brachah was due to you, and not due to your hard work!
As the Gemara says in B'rachos (42a) 'With a Talmid-Chacham comes Berachah'.
A form of witchcraft based on the twittering of birds (Ramban, Parshas Shoftim).
Even if he would return to be poor, Lavan enjoyed 14 years of prosperity in exchange for his daughters, and now he has sons in place of them. Why should the sale be Batel?! (PF)
How can one reconcile Lavan's apparent belief in Hashem with his statement later (in 31:30) "Lamah Ganavta es Elohai"?
Oznayim la'Torah #1: He was quite happy to believe in Hashem if it was to flatter Yakov.
Oznayim la'Torah #2: He believed in Hashem be'Shutfus - in partnership with idolatry.