What is the gist of the covenant that Lavan made with Ya'akov? Why did he begin with the word "v'Atah"?
Seforno: What he is saying is 'Now that it is clear that I am not out to harm you, 1 let us make a covenant that will also guarantee that you will not harm me!'
To whom (what) was he referring when he said 'v'Hayah l'Eid Beini u'Veinecha'?
Rashi: He was referring to Hakadosh-Baruch-Hu. 1
Ramban 2 : He was referring to the covenant, 3 including oaths and curses that would take effect on whoever would break it. Alternatively, he was referring to something concrete on which the covenant would take effect. 4
רש"י: והיה לעד - הקדוש ברוך הוא: אולי הברית תהיה לעד?
גור אריה: 'ברית' זה לשון נקבה, ואם הברית מעידה, צריך היה לכתוב 'והייתה לעד'.