Why did Ya'akov 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.
As the Gemara says in Yoma (38b) 'One person cannot touch what is designated for another as much as a hair's breadth'.