Musar su Salmi 72:10

The Midrash tells us that the number of Israelites would never be fewer than 600,000. Dogs is a hyperbole for קליפה. Our sages in Baba Kama 60 say that it is the dogs that call out: "the angel of death is coming!" When the firstborn of Egypt were slain and the Jews were about to leave Egypt, the Torah described the dogs as having remained silent towards the Israelites (Exodus 11,7). The hyperbole used in the Midrash saw Jacob as appointing the dogs as guards over the sheep i.e. Jewish people in exile, so that they would not become further infested with the pollutants of the original serpent. The opinion cited that he used 1,200,000 dogs is in accordance with the view expressed in Shabbat 88 that when Israel committed the sin of the golden calf, 1,200,000 destructive angels descended in order to remove each man's jewelry from him. This had been bestowed on them at the time Israel volunteered to accept the Torah. Jacob wanted to make these dogs subservient to the flocks, i.e. the Jewish people, in order to fulfil what is written in the verse in Proverbs 16,7: "When a man's ways please G–d, He makes even his enemies be at peace with him." We have stated that צאן is an allusion to the people of Israel. An interesting mnemonic note may be the halachic term צאן ברזל, which is used for inalienable property of the wife which returns to her family regardless of any rights of the husband. The four wives of Jacob produced the twelve tribes. Their names were: בלהה, רחל, זלפה, לאה. The first letters of their respective names spell ברזל, something that will endure under all circumstances.