What does it mean that the brothers could not speak to Yosef “for peace”?
(37,4) “And his brothers saw that their father loved him more than all his brothers, and they hated him, and they could not speak to him לשלום (for peace - peacefully).”
We can explain this posuk according to the gemora in Berachos 64a which teaches that when someone takes leave of his friend, he should not say to him "Go in peace (בשלום)", but rather "Go to/for peace (לשלום)". Because behold, Yisro said to Moshe, “Go to/for peace”, and he went up and succeeded. But Dovid said to Avshalom “Go in peace”, and he went and became hung in a tree.
This is what our posuk is saying, that the brothers who hated Yosef were not able to speak to him לשלום.
How did the brothers show that Yosef’s dream must be false?
(37,8) “And his brothers said to him: Will you surely reign over us, or will you surely govern over us? (literally - if govern, you will govern over us).”
There are many questions that can be asked here. However, we can explain it from that which is written in Tehillim 22:29 “For to Hashem is the Kingship, and He rules over the nations”. A king is one who is appointed by the will of the people, and the word for word king (מלך) is derived from the word which means taking counsel (המלכה), because the counsel of the people is sought whether to appoint this person over them to be their king. But a ruler is one who rules the people by force.
Thus the posuk in Tehillim means that “to Hashem is the Kingship”, because Yisrael accepts upon themselves the yoke of His Kingdom willingly, but “He rules over the nations” with force, even against their will. But about the future it says in Zechariah 14:9 “And Hashem will be King over all the earth”, because the whole world will accept the yoke of His Kingdom willingly.
Similarly, we can explain here that they said here in wonderment “will you surely reign over us?” because kingship has to be with our agreement, and this you certainly do not have, because we hate you. So how could we willingly agree to appoint you as king over us? “If govern”, that is, if you had seen in a dream that you will govern us, this could possibly be, that “you will govern (even) us” some time in the future, to take revenge from us. But that you will be king over us is impossible. And since that which you saw that you will be king is a falsehood, so too that which you saw that you will govern is also false, since the rule is that when one of two things in a certain matter cannot be, than the other also cannot be.
A perfect explanation of a difficult Rashi.
(37,18) “And they saw him from afar, and before he had drawn near to them, they plotted against him (ויתנכלו אותו) to kill him.”
Rashi explained the last phrase: ויתנכלו - they became filled with plots and cunning, אותו - similar to אתו and עמו, that is, it means to him, against him.
Behold, many explanations have been given to explain these words of Rashi. But it seems to me that Rashi was coming to explain a difficulty, because the word ויתנכלו means filled with plots, meaning that they themselves became filled with evil thoughts how to do evil to Yosef. Like the posuk in Bamidbar 25:13 “which they plotted against you in the incident of Peor”, meaning that the Midianites had become filled with evil thoughts to do evil to Yisrael, and also the posuk in Tehillim 105:25 “to plot against His servants”, meaning that the Egyptians had become filled with evil thoughts to do evil to Yisrael, who are the servants of Hashem. If so, how could our posuk say ויתנכלו אותו, which implies that they filled him, Yosef, with evil thoughts. It should have said ויתנכלו אליו or ויתנכלו עליו, which means they were filled with evil thoughts against him or about him, like the Targum Onkelos translated the posuk "and they thought about him to kill him".
Therefore, Rashi answered that behold, at the end of parshas Vayikra (5:23) it is written “and he shall return the stolen article that he stole, or the deposit which was deposited אתו”. And perforce, this last word does not mean what it usually means - 'with him', but rather it means 'to him'. That is, to return the deposit which was deposited to him in his hand. (Or Rashi could be referring to the posuk at the end of parshas Ki Sisoh (34:35), “until he would come to speak אתו”, where again, it does not mean 'with Him', but rather 'to Him'). And in Megillas Esther 6:3 it is says “and the king’s servants who minister before him said: Nothing was done עמו”, and there too you must explain the word to mean 'to him'.
So now the words of Rashi have been explained completely. He explained that אותו is similar to אתו in the end of parshas Vayikra or the end of parshas Ki Sisoh, and similar to עמו that is written in Megillas Esther. Because in both places they are explained to mean 'to him'. Here also, the posuk means that “they plotted to him” - against him.