Or HaChaim on Numbers 24:9/אור החיים על במדבר כ״ד:ט׳

1 כרע שכב כארי, "He couched, he lay down like a lion, etc." Bileam extols the prowess of the Jewish people as being evident even when the nation is in repose, unarmed, etc. The nation relies on its reputation and does not fear attack even when lying down. The reason Bileam uses two different names for lions in this verse is once again in accordance with the way he divided the Jewish people into Jacob and Israel, i.e. into the average Israelite and the elite, respectively.

2מברכיך ברוך וארריך ארור, "the ones who bless you is blessed, those who curse you is cursed." Why are the respective subjects in this verse described in the plural whereas their respective victims or beneficiaries are described in the singular? The reason is simple. Bileam did not want to bless more than a single Jew. He used himself as a model; his well known avarice would not allow him to proliferate blessings. When he appears to have used the same approach in describing the people who curse the Israelites, he limited the negative fallout for people who curse the Israelites to a single one. In other words, although many may attempt to curse Israel only one of them will wind up cursed himself. Bileam used this stratagem so that he himself would not necessarily be included if he succeeded to curse the Israelites. Possibly, he had another evil intent here. When he said "those who bless you is blessed," he meant that the blessing should be fulfilled on the person doing the blessing who would remain blessed as a result of pronouncing it. He mentioned the second alternative, i.e. that those who curse Israel will be cursed only afterwards so as to ensure that he had already secured an enduring blessing for himself by having blessed Israel first. G'd made certain that Bileam's curse, i.e. his evil intent, boomeranged, so that he himself wound up accursed both in this world and in the hereafter (compare Sanhedrin 90 where we are told that Bileam forfeited his share in the hereafter).