Numbers 22:12

And God said unto Balaam, thou shalt not go with them
Which is a denial of the first thing Balak requested, "come now, therefore" ( Numbers 22:6 )

thou shall not curse the people;
which was the principal thing desired, and in order to which he was solicited to go with the messengers; but this is absolutely forbidden:

for they are blessed;
by the Lord himself, with an irrevocable blessing, and therefore it would be vain and fruitless, as well as dangerous for him to attempt to curse them, ( Genesis 12:3 ) this may have a special respect to the blessing of Jacob by Isaac, which could not be reversed by the solicitations of Esau, and which descended to Jacob's posterity, the Israelites, ( Genesis 27:33 ) .