Why did Yaakov decline any assistance from Lavan?
Seforno: Because, since he would now be self-employed, Hashem would provide him with all his requirements, and there was no need to deprive Lavan of one cent of what was designated for him. 1
Tosfos ha'Shalem (1, citing R. Efrayim): I do not need gifts from you, for my father blessed me, and Hashem promised not to abandon me.
Bechor Shor: I will not take anything from what you have now, only from Davar she'Lo Ba l'Olam.
Malbim: Lavan said, I agree that you deserve extra wages for the past. Yaakov denied this - I worked for your daughters, and I may take them where I desire! If you want me to stay, do the following....
Ha'amek Davar, citing R. Yitzchak of Volozhin: If I will be in need, you will not give to me anything. You will find excuses to exempt yourself. Therefore, I request....
As the Gemara says in Yoma (38b) 'One person cannot touch what is designated for another as much as a hair's breadth.'