How do Lavan's words counter Yaakov's claim?
Seforno: He maintained that, even had he switched the conditions, or sent him away empty-handed, he would have been acting within his rights, seeing as everything that Yaakov owned, he obtained by trickery. Indeed, he added, he (Lavan) was perfectly entitled to take them all. 3
Ramban: He pointed out that he could not possibly harm his own daughters and their children, who were born in his home. And he claimed that he had run after him, not to do them harm, but to see what good he could do on their behalf.
Ohr ha'Chayim #1: I could show what you took from me, but I do not want to shame my [grand]sons and daughters, or go to judgment with them.
Ohr ha'Chayim #2: How can I prove via Simanim what is mine? [Your family is] my grand]sons and daughters - they constantly use my Kelim, and know the Simanim better than I do!
Ohr ha'Chayim #3: You rebuked me for looking through all your Kelim. They are all mine! I would not do so to a stranger.
Malbim, Ha'amek Davar: I pursued you for the sake of my daughters, lest you take additional wives, and lest my property (that you amassed) fall to sons from other wives. I came to make a Bris about this with you!
Ha'amek Davar: I did not search through everything for my Kelim. Really, it is all mine - if I was adamant, I would keep it at all! I was concerned only for my gods. "V'Yikachashu Oyevecha Lach" (Devarim 33:29) was fulfilled. 4
Oznayim la'Torah: In answer to Yaakov's claim, "Mah Matzasa mi'Kol Kelei Beisecha?"(31:37), Lavan responded that the girls, the sons, the sheep and everything that Yaakov has belongs to him. In answer to "Ki Amarti Pen Tigzol Es Benosecha" (31:31), he pointed out that he loved his daughters and their children dearly and would never do them harm.
They only explain the latter part of the Pasuk.
Gur Aryeh: Rashi explains Mah (what) as Eich (how). Lavan wasn't unsure of what action to take against them; rather, he was saying it would be inconceivable that he would do anything....
However, he will not do so, for then he would need to sustain them.
Ha'amek Davar: This was also a Siman for future generations. When Nochrim pursue and accuse Jews and do not find what they suspected, they deny that this was why they pursued.
Why did Lavan add the word "l'Eileh" (to these)?
Radak: To daughters as good as these, how could I do anything [bad]?!
Ohr ha'Chayim #1: What can I do to this property? [If I take it, like I am entitled to,] what will be for my daughters and their children?
Ohr ha'Chayim #2: What can I do to harm my daughters? Even though they consider themselves like 'Eleh' (strangers) today, based on their deeds, they are my daughters.
The Torah makes it clear that had Hashem not appeared to threaten Lavan, he would indeed have attacked his own daughters and grandsons (31:29); and as Chazal teach, 'Lavan sought to uproot everything' (Hagadah Shel Pesach). Why did Lavan hate Yaakov so?
Maharal (Gevuros Hashem Ch. 54, p. 237): Lavan hated Yaakov without tangible cause, because they were diametric opposites. Yaakov justified his and the world's existence, whereas Lavan was an Aramean. 1
How can Lavan say that everything is his? He himself (Bereishis 30:27) said that Hashem blessed him due to Yaakov!
Ohr Yechezkel (Midos p. 15-16): This shows what lowliness is possible in a person.
How can Lavan say "the sons are mine"? Yaakov fathered them!
He could say so about Bnei Bilhah and Zilpah, who were slaves. What is his claim to Bnei Leah and Rachel?! (PF)
Why did Lavan say, "what can I do to these today"?
Tosfos ha'Shalem (6, citing R. Efrayim): Had I known you were leaving, I would have given to them pillows, blankets and household Kelim. Here, I have nothing to give to them.
Refer to 31:43:2:3.
Why does it say, "their children that they bore"?